Alarm system

ABSTRACT

Described herein are alarm systems for suction devices for reduced pressure therapy. Alarms systems provide alerts to the patient and/or practitioner regarding the ability of the suction device to continue to provide negative pressure to a tissue region. Alarm systems comprise a sensor mechanism, which is capable of detecting the position of a slidable seal within the suction device, and generating an alert. Certain variations of alarms systems comprise magnetic field sensitive switches and/or electric switches. Other variations of alarm systems comprise rotary encoders to detect the motion and location of constant force springs, which signal the notification mechanism to issue alerts accordingly. Described herein are alarm devices configured to retain a suction device therein and to attach the suction device to a patient. The alarm devices disclosed herein detect the depleted state of the suction device and are capable of retaining the suction device in a plurality of orientations.

RELATED REFERENCES

This application is a continuation of U.S. application Ser. No.13/175,744, filed Jul. 1, 2011, which claims benefit from U.S.Provisional Application Ser. No. 61/372,419, filed Aug. 10, 2010, U.S.Provisional Application Ser. No. 61/372,843, filed Aug. 11, 2010, U.S.Provisional Application Ser. No. 61/372,837, filed Aug. 11, 2010, andU.S. Provisional Application Ser. No. 61/470,423, filed Mar. 31, 2011,each of which is hereby incorporated by reference in its entirety.

BACKGROUND

Research has shown that applying reduced pressure to a tissue wound mayprovide several beneficial effects. For example, applyingsub-atmospheric pressure to a wound may lead to retraction of thedamaged tissue edges and thus may expedite healing by facilitating woundcontraction. Reduced pressure wound therapy may also provide mechanicalstimulation to the damaged tissue, which may release growth factors tothe wound bed to promote healing. In some cases, applying suction to awound may remove necrotic tissue from the wound bed and may help toreduce bacterial load.

In light of these and other benefits of reduced pressure tissue therapy,methods and devices that ensure a reliable application of reducedpressure to a wound may be desirable.

BRIEF SUMMARY

Alarm systems suitable for use with suction devices for reduced pressurewound therapy are described below.

Disclosed herein is a reduced pressure therapy device that may comprisea suction device with a suction chamber and a slidable seal within thesuction chamber, a magnet coupled to the slidable seal, and an alarmdevice comprising a sensor that is configured to detect the location ofa magnet within the suction chamber. The alarm device may be configuredto retain the suction device, and may also comprise a notificationmechanism that is configured to generate an alert based on the locationof the magnet. In some variations, the alarm device is configured to beelectrically activated when retaining the suction device. The alarmdevice may comprise a conductive element along an outer surface and thealarm device comprises two or more connectors. The conductive elementmay be configured to provide an electrical conduit between the two ormore connectors to electrically activate the alarm device. In somevariations, the alarm device may comprise a tactile power switchconfigured to be pressed when the alarm device retains the suctiondevice.

Optionally, a suction device may comprise a fluid absorption materialretained by a carrier within the suction chamber. In some variations,the fluid absorption material may be bonded to an outer surface of thecarrier. Alternatively or additionally, the carrier may comprise a pouchconfigured to releasably retain the fluid absorption material. A suctiondevice may also comprise a screen located between the carrier and thedistal portion of the suction chamber. In some variations, the screenmay be adhesively attached to the suction chamber or may be adhesivelyattached to the carrier.

Disclosed herein is a reduced pressure therapy system that may comprisea suction device comprising a suction chamber with an inlet opening anda slidable seal within the suction chamber. The reduced pressure therapysystem may also comprise an expandable fluid absorbent material locatedwithin the suction chamber and a screen configured to block displacementof the expandable fluid absorbent material out of the suction device.The screen may also be configured to sequester the expandable fluidabsorbent material in a selected region of the suction chamber. Thescreen may be located within the suction chamber. In some variations,the expandable fluid absorbent material, prior to any fluid absorption,may have a fixed location in the suction chamber that is independent ofsuction device orientation. In some variations, the expandable fluidabsorbent material may be retained by a carrier structure. The carrierstructure may be retained at a selected region in the suction chamber.For example, the expandable fluid absorbent material may be bonded tothe carrier structure, and in some cases, may be bonded on a surface ofthe carrier structure. Additionally or alternatively, the expandablefluid absorbent material may be releasably contained within the carrierstructure. The expandable fluid absorbent material may be woven into thecarrier structure. In some variations, the carrier structure comprises apermeable pouch. One variation of a permeable pouch may comprise twopermeable layers sealed together. Optionally, the expandable fluidabsorbent material may comprise one or more disinfecting agents.

In some variations of a suction device fluid retention assembly, thecarrier structure may comprise an aperture therethrough, and may belocated within the suction chamber such that the aperture is alignedwith the inlet opening of the suction chamber. The screen of the fluidretention assembly may be interposed between the inlet opening and thecarrier structure.

In some variations of a suction device fluid retention assembly, thecarrier structure may comprise a permeable pouch. The permeable pouchmay comprise two permeable layers sealed together, and may optionally besealed together along the perimeter of each of the layers. The permeablepouch may be attached to the screen of the fluid retention assembly. Insome variations, the expandable fluid absorbent material may bereleasably contained within the carrier structure.

Methods of treating a patient using reduced pressure therapy are alsodescribed herein. One variation of a method for treating a patient maycomprise providing suction to a treatment site using a suction deviceand absorbing fluid from a treatment site using a fluid absorbentmaterial. Prior to fluid absorption, the fluid absorbent material mayhave a fixed location within the suction device. Some methods mayfurther comprise blocking expulsion of the fluid absorbent materialusing a screen located within the suction device. In some variations,the method may use a suction device comprising a suction-generatingchamber with a sliding seal, where the fluid absorbent material and thescreen are located within the suction-generating chamber.

One variation of a method for treating a patient may comprise providingsuction to a treatment site using a suction device comprising asuction-generating chamber, absorbing fluid from a treatment site usinga fluid absorbent material, and blocking expulsion of the fluidabsorbent material using a screen located within the suction-generatingchamber. In some variations, the fluid absorbent material may have afixed location within the suction-generating chamber.

Provided herein is a reduced pressure therapy system comprising asuction device comprising a suction chamber, a expandable fluidabsorbent material located within the suction chamber; and a screenconfigured to sequester the expandable fluid absorbent material in aselected region of the suction chamber. The suction chamber may comprisean inlet opening at a distal portion of the chamber and a slidable sealtherein. In some variations, the expandable fluid absorbent material maybe sequestered in the selected region of the suction chamber that isindependent of suction device orientation. For example, the screen maysequester the expandable fluid absorbent material at the distal portionof the suction chamber. Alternatively or additionally, the expandablefluid absorbent material may be retained by a carrier structure, whereinthe carrier structure is retained at the selected region in the suctionchamber. In some variations, the expandable fluid absorbent material maybe bonded to the carrier structure, such as to a surface of the carrierstructure. The expandable fluid absorbent material may alternatively oradditionally be woven into the carrier structure. Optionally, theexpandable fluid absorbent material may comprise one or moredisinfecting agents.

In some variations, the carrier structure may comprise an aperturetherethrough, and the aperture may be aligned with the inlet opening ofthe suction chamber. The screen may be interposed between the inletopening and the carrier structure. In some variations, the expandablefluid absorbent material may be releasably contained within the carrierstructure. The carrier structure may comprise a permeable pouch, and insome variations, the permeable pouch may be attached to the screen. Thepermeable pouch may comprise two permeable layers sealed together. Thetwo permeable layers may be sealed together along the perimeter of eachof the layers.

Another variation of a reduced pressure therapy system may comprise achamber with a movable magnet and a magnet sensitive mechanismconfigured to detect a magnetic field of the movable magnet. The chambermay be a vacuum-generating chamber configured with a fixed wall and amovable wall. In some variations, the movable wall may comprise aslidable seal, while in other variations, the vacuum-generating chambermay comprise a bellows mechanism, where the magnet is located on themovable wall of the bellows. The chamber may also be a fluid trapchamber, and in some variations, may comprise a float, where the floatis coupled to the movable magnet. In some variations of a reducedpressure therapy system, the magnet sensitive mechanism may comprise oneor more reed switch, where the reed switch may normally have an openstate. A plurality of reed switches may be provided along a movementaxis of the movable magnet. Alternatively, the reduced pressure therapysystem may comprise a Hall effect sensor. The magnet sensitive mechanismmay be coupled to a clip configured to attach to the vacuum system. Incertain variations, the reduced pressure therapy system may furthercomprise an indicator mechanism connected to the magnet sensitivemechanism and configured to provide at least one signal indicated of aposition of the movable magnet. The at least one signal may be a visual,auditory, or tactile signal.

Another variation of a reduced pressure therapy system may comprise anon-electrically powered vacuum-generating chamber configured with aposition element located on a movable region of the vacuum-generatingchamber, and a circuit comprising a first state when the positionelement is at a first location and a second state when the positionelement is at a second location. The circuit may be configured to bedetachably attachable to the vacuum-generating chamber. The circuit mayalso comprise an electrical power source and a signaling mechanism,where the signaling mechanism is configured to generate at least onesignal that is an audio, visual, and/or tactile signal. In somevariations, the signaling mechanism may be configured to generate awireless signal, or may be configured to transmit an alarm signal to aremote monitoring display.

The position element of a reduced pressure therapy system may comprisean electrical pathway having a first end located about a first surfaceof the chamber and a second end located about a second surface of thechamber, and the first state of the circuit is an open circuit and thesecond state of the circuit is a closed circuit state. In somevariations, the first surface of the chamber may be an outer surface ofthe chamber, and in some cases, the chamber may be a bellows chamber. Inother variations, the first surface of the chamber may be an innersurface of the chamber, and in some cases, the movable region of thevacuum-generating chamber may be a slidable sealing wall.

The position element of a reduced pressure therapy system may be amagnet. In some variations, the circuit may be a Hall effect sensorcircuit and/or a reed switch circuit.

Also described below are methods for treating a patient using a reducedpressure therapy system. One example of a method for treating a patientmay comprise treating a patient with a reduced pressure therapy systemcomprising a non-electrically powered vacuum mechanism and anelectrically powered alarm system, wherein the electrically poweredalarm system comprises a magnetic sensitive mechanism, and using amagnetic sensitive mechanism to indicate a state of the vacuummechanism. The magnetic sensitive mechanism may comprise a reed switch,where the reed switch has a sensitivity of about 10 to about 60Ampere-Turns. The reed switch may be in a normally open state. Themethod may also comprise detaching the vacuum mechanism from the alarmsystem and attaching a new vacuum mechanism to the same alarm system.The method may also comprise activating the new vacuum mechanism.

Another variation of a reduced pressure therapy device may comprise asuction device with a suction chamber and a slidable seal within thesuction chamber, where the slidable seal is oriented transversely to thelongitudinal axis of the suction chamber, a magnet coupled to theslidable seal transversely to the longitudinal axis of the suctionchamber, and an alarm device comprising one or more sensors that may beconfigured to detect the location of a magnet within the suctionchamber. The alarm device may be configured to retain the suction devicealong the longitudinal axis. The alarm device may comprise a firstsensor at a distal portion of the alarm device, and a second sensor at aproximal portion of the alarm device, where the first and second sensorsare configured to detect the location of the magnet. Additionally, thealarm device may comprise a notification mechanism configured togenerate an alert when the magnet is aligned with the second sensor.

Another variation of a reduced pressure therapy device with an alarmsystem using a magnetic sensor mechanism may comprise a suction device,the suction device comprising a suction chamber, a slidable seal withinthe suction chamber, and a central shaft coupled to the slidable seal, amagnet coupled along the longitudinal axis of the central shaft, and analarm device configured to retain the suction device. The alarm devicemay comprise a sensor configured to detect the position of the magnetwithin the suction chamber, and a notification mechanism configured togenerate an alert according to the position of the magnet.

Some variations of a reduced pressure therapy device with an alarmsystem may comprise a suction device comprising a suction chamber with alongitudinal axis from a proximal portion to a distal portion, aslidable seal disposed within the suction chamber transverse to thelongitudinal axis, and a shaft fixedly attached to the slidable seal,wherein the shaft is oriented along the longitudinal axis, a magnetcoupled to the shaft along the longitudinal axis, and an alarm deviceconfigured to retain the suction device. The alarm device may comprise asensor configured to detect the position of the magnet within thesuction chamber, and a notification mechanism configured to generate analert according to the position of the magnet.

Certain variations of reduced pressure therapy devices with an alarmsystem may use an electrical switch mechanism. For example, a reducedpressure therapy device may comprise a suction device comprising asuction chamber and a slidable seal within the suction chamber, anelectrical switch coupled to the slidable seal, and an alarm deviceconfigured to retain the suction device. The attachment feature maycomprise a notification mechanism configured to generate an alert whenaligned with the electrical switch.

Another variation of a reduced pressure therapy device may comprise asuction device comprising a suction chamber and a slidable sealtransversely disposed within the suction chamber, an electrical currentconduit coupled to the slidable seal, wherein the conduit extends acrossthe entire transverse width of the slidable seal, and an alarm deviceconfigured to retain the suction device. The alarm device may comprise anotification mechanism with a first electrical contact and a secondelectrical contact opposite the first electrical contact, wherein thenotification mechanism is configured to generate an alert when the firstand second electrical contacts are connected by the current conduit.

Certain variations of reduced pressure therapy devices may comprise asuction device comprising a suction chamber and a slidable seal withinthe suction chamber, a magnet coupled to the slidable seal, and an alarmdevice configured to retain the suction device. The alarm device maycomprise a magnetic field sensitive switch configured to activate anotification mechanism to generate an alert according to the location ofthe magnet. In some variations, the magnetic field sensitive switch maybe a reed switch. Alternatively or additionally, the magnetic fieldsensitive switch may comprise a sensor to detect the location of themagnet within the suction chamber.

Other variations of reduced pressure therapy devices may comprise asuction device comprising a suction chamber and a slidable sealtransversely disposed within the suction chamber, a magnet coupled tothe slidable seal, and an attachment feature configured to retain thesuction device along the longitudinal axis. The slidable seal may beoriented transversely to the longitudinal axis of the suction chamber.The attachment feature may comprise a reed switch at a proximal portion,where the reed switch is configured to be closed when the magnet is ator near the proximal portion. The attachment feature may also comprise anotification mechanism configured to generate an alert when the reedswitch is closed.

Disclosed herein is another variation of a reduced pressure therapydevice that may comprise a suction device with a suction chamber and aslidable seal within the suction chamber, a magnet coupled to theslidable seal, and an alarm device comprising a sensor that isconfigured to detect the location of a magnet within the suctionchamber. The alarm device may be configured to retain the suctiondevice, and may also comprise a notification mechanism that isconfigured to generate an alert based on the location of the magnet. Thealarm device may optionally comprise a tactile power switch configuredto be pressed with the alarm device retains a suction device therein.The suction device may have a charged configuration and a depletedconfiguration. In the charged configuration, the magnet may not bedetectable by the sensor, while in the depleted configuration, themagnet may be detectable by the sensor. In some variations, the alarmdevice is configured to detect the configuration of the suction deviceregardless of the orientation of the suction device within the alarmdevice. In some variations, the sensor may comprise a first reed switchat a first location and a second reed switch at a second locationseparate from the first location. The alarm device may retain thesuction device such that in the charged configuration, the magnet islocated between the first and second locations and not detectable byeither reed switch, and in the depleted configuration, the magnet isdetectable by at least one reed switch. Optionally, the first and secondlocations may define a first line with a first midpoint, wherein thetravel path of the magnet from charged to depleted configurations definea second line with a second midpoint. The first and second midpoints areoffset from each other. In some variations, the distance of the magnetto the nearest reed switch is less in the depleted configuration than inthe charged configuration. The suction device may be retained in thealarm device in two or more orientations, e.g., four orientations. Inone embodiment, the suction device may be retained within the alarmdevice in a first orientation and a second orientation, where the secondorientation is the first orientation rotated 180 degrees around atransverse and/or longitudinal axis of the suction device. In anothervariation of a reduced pressure therapy device, the alarm device maycomprise a reed switch at a proximal location of the alarm device, wherethe alarm device retains the suction device such that in the chargedconfiguration, the magnet is not detectable by the reed switch, and inthe depleted configuration, the magnet is detectable by the reed switch.

Disclosed herein is another variation of a reduced pressure therapydevice that may comprise a suction chamber with a slidable seal therein,a magnetic element or magnet coupled to the slidable seal, a firstalignment protrusion at a distal portion, and a second alignmentprotrusion at a proximal portion. The suction device may have a chargedconfiguration and a depleted configuration, wherein the distance of themagnet to the first alignment protrusion in the charged configuration isgreater than the distance of the magnet to the second alignmentprotrusion in the depleted configuration. In another variation of areduced pressure therapy device, the distance of the magnet to thedistal end of the suction chamber in the charged configuration isgreater than the distance of the magnet to the proximal end of thesuction chamber in the depleted configuration. jump

BRIEF DESCRIPTION OF THE DRAWINGS

FIGS. 1A and 1B are perspective views of a variation of a reducedpressure therapy device in a mechanically uncharged and chargedconfiguration, respectively; FIGS. 1C and 1D are superior and sideelevational views of the device in FIGS. 1A and 1B in an activated andpartially depleted state.

FIG. 2A is a perspective view of another variation of a suction devicefor reduced pressure therapy comprising a magnetic alarm system and analarm device; FIGS. 2B and 2C are superior component views of thesuction device and alarm device, in charged and depleted states,respectively.

FIG. 3A is a superior component view of another variation of a suctiondevice in a mechanically charged configuration, comprising an alarmsystem with a magnetic sensor mechanism; FIG. 3B is a superior componentof another variation of a suction device in a mechanically chargedconfiguration with a magnetic sensor mechanism.

FIG. 4A depicts one variation of a suction device for reduced pressuretherapy comprising an alarm system with an electric switch mechanism ina mechanically charged configuration; FIG. 4B is a depiction of thesuction device of FIG. 4A in a depleted configuration; FIG. 4C is ananterior perspective component view of the suction device and an alarmdevice of FIG. 4A; FIG. 4D is a posterior perspective view of thesuction device and alarm device of FIG. 4A with an alarm device; FIG. 4Eis a side elevational view of the alarm device of FIG. 4C.

FIG. 5 depicts one example of a notification circuit that may be used analarm system for reduced pressure therapy devices.

FIG. 6A is a schematic representation of a spring assembly in anextended configuration with a rotary sensor that may be used in asuction device; FIG. 6B depicts the spring assembly of FIG. 6A in aretracted configuration.

FIGS. 7A and 7B are schematic depictions of a reed sensor in an open anda closed configuration, respectively.

FIG. 8 depicts another variation of a suction device for reducedpressure therapy comprising an alarm system with one or more reedsensors, where the slidable seal of the suction device comprises one ormore magnets.

FIG. 9 is a block diagram of one variation of an alarm system that maybe used with reduced pressure therapy devices.

FIG. 10A depicts a block diagram representation of another variation ofan alarm system that may be used with reduced pressure therapy devices.FIGS. 10B to 10D depict examples of circuits that may be implemented inthe alarm system of FIG. 10A. FIG. 10B depicts one variation of anorientation circuit; FIG. 10C depicts one variation of a sensor circuit;FIG. 10D depicts one variation of an amplifier circuit.

FIG. 11 is a schematic of exemplary alarm system components as arrangedon a printed circuit board.

FIG. 12A is a perspective view of one variation of an alarm device. FIG.12B is a perspective view of a suction device coupled to the alarmdevice of FIG. 12A.

FIG. 13 is state machine diagram that depicts one variation of a statemachine that may be programmed into a microcontroller of an alarm systemthat may be used with reduced pressure therapy devices.

FIG. 14A is a schematic representation of a suction device with aconductive element; FIG. 14B depicts a first orientation of the suctiondevice of FIG. 14A; FIG. 14C depicts a second orientation of the suctiondevice of FIG. 14A; FIG. 14D is a perspective view of a variation of asuction device with a conductive element; FIG. 14E is a perspective viewof an alarm device with one or more connectors.

FIGS. 15A and 15B are perspective views of a variation of an alarmdevice that may be used with a suction device; FIG. 15C is a perspectiveview of one variation of a suction device that may be retained withinthe alarm device of FIGS. 15A and 15B; FIG. 15D is a superior view ofthe back of the attachment and suction devices of FIGS. 15A-15C.

FIG. 16A is an elevational component view of one variation of a suctiondevice for reduced pressure wound therapy; FIG. 16B is a superior viewof one variation of a fluid retention assembly comprising a pouch thatmay be used with the suction device of FIG. 16A.

FIG. 17A is a perspective view of another variation of a fluid retentionassembly comprising an absorbent pad and filter; FIG. 17B is a side viewof the fluid retention assembly of FIG. 17A; FIG. 17C is a perspectiveview of the absorbent pad of the fluid retention assembly of FIG. 17A;FIG. 17C is top view of the filter of the fluid retention assembly ofFIG. 17A; FIG. 17D is a top view of a mesh of the fluid retentionassembly of FIG. 17A.

FIG. 18A is a schematic depiction of a suction device with a fluidretention assembly comprising a pouch; FIG. 18B is a schematic depictionof a suction device with a fluid retention assembly comprising a mesh;FIG. 18C is a schematic depiction of a suction device with a fluidretention assembly comprising an absorbent pad; FIG. 18D is a schematicdepiction of a suction device with a fluid retention assembly comprisinga pouch and a mesh; FIG. 18E is a schematic depiction of a suctiondevice with a fluid retention assembly comprising an absorbent pad and amesh.

FIG. 19A is a schematic depiction of one orientation in which a suctiondevice may be retained in an alarm device; FIGS. 19B and 19C areschematic depictions of the relative positioning between a suctiondevice and an alarm device; FIG. 19D is a example of an alternateorientation in which a suction device may be retained in an alarmdevice.

FIG. 20 is a schematic depiction of another variation of an alarm devicecomprising a single sensor and a suction device.

DETAILED DESCRIPTION

Various types of reduced pressure therapy systems may be used dependingon the severity of the tissue wound and the activity level of thepatient. In some cases, reduced pressure tissue therapy systems mayextract tissue exudates, e.g., wound exudates and interstitial fluids,while providing reduced pressure therapy. Some reduced pressure tissuetherapy systems comprise a suction device with an open pressure supply,e.g., continuous electric pump. These systems typically are noisy, andtheir bulkiness and weight often restricts the mobility of a patient.Patients that desire greater mobility may use a reduced pressure tissuetherapy system comprising a wearable suction device that does not relyon power from an electrical source, e.g., non-electrically powered.

FIG. 1A is a perspective view of one example of a wearable suctiondevice 100 that may be used in reduced pressure tissue therapy. Asdepicted there, the suction device 100 may comprise a suction chamber110, a suction generating mechanism (not shown), and a sliding sealassembly 160 that is movably retained in the suction chamber 110. Onevariation of a suction generating mechanism of the suction device 100 isdepicted in FIGS. 1C and 1D, and may comprise one or more springs 195,and the proximal side of the sliding seal assembly 160 may be coupled toone or more springs 195. The springs 195 may be constant force springs,or any other type of springs that may be used to apply a force on thesliding seal assembly 160 in a proximal direction. The suction device100 may also comprise a housing 102 that may retain the suction chamber110. The housing 102 may comprise a proximal cap 130 with proximalopening 132 and a distal cap 120 with a distal port 142. In somevariations, the distal cap 120 may comprise a tube fitting 140configured for interfacing with a tube (e.g., a tube connected to adressing) such that the tube is in fluid connection with the suctionchamber. In some variations, the tube fitting 140 may be detachable fromthe distal cap 120. Negative pressure generated in the suction chamber110 may be conveyed to a tissue site through a distal aperture in thesuction chamber leading to the distal port 142 of the tube fitting 140.Tubing connected to the distal port 142 may allow the negative pressureto be directed to the tissue site and/or dressing. The suction devicemay also comprise an activation tool 190 that may be inserted throughthe proximal opening 132, where the activation tool 190 is configured tomechanically charge the suction device 100, for example, by urging thesliding seal assembly to certain positions in the suction chamber. Insome variations, the activation tool 190 may be releasably snap-lockedin the proximal opening 132, which may help secure the sliding sealingassembly 160 in a certain position within the suction chamber 110. Forexample, the activation tool 190 may comprise tabs 191 with protrusions193 such that when the tabs 191 are released, the protrusions 193 may beengaged in one or more grooves in the proximal cap 130 at or near theproximal opening 132, thereby retaining the activation tool in thesuction chamber. When the tabs 191 are pressed (e.g., squeezed), theprotrusions 193 may disengage from the grooves and allow the activationtool 190 to be withdrawn from the proximal opening 132. FIG. 1A depictsthe configuration of the suction device 100 before it is activated,where the sliding seal assembly 160 is located at a proximal portion 114of the suction chamber, and where the activation tool 190 is insertedinto the proximal opening 132 of the proximal cap 130 but has not yetdisplaced the sliding seal assembly 160. The suction chamber 110 maycomprise a translucent or optically clear material, or an opaquematerial with or without a translucent or optically clear window.

FIG. 1B depicts the suction device 100 in a mechanically chargedconfiguration. To mechanically charge the suction device 100, theactivation tool 190 may be pushed through the proximal opening 132 toextend or distally displace the sliding seal assembly 160 from theproximal portion 114 of the suction chamber 110 to a distal portion 106of the suction chamber 110. Depending upon the particular configuration,the activation tool 190 may be pushed until the sliding seal assembly160 contacts a wall of the distal cap 120, until it is adjacent thedistal end wall of the suction chamber 110, until the springs 195 aremaximally extended, and/or until mechanical interference between theactivation tool 190 and the proximal cap 130 resist further insertion.Urging the sliding seal assembly 160 to the distal position 106 asdepicted in FIG. 1B may in turn extend the springs 195 that are attachedto the proximal side of the sliding seal assembly. This may generatepotential energy within the springs 195. Other variations of wearablesuction devices that may be used in a reduced pressure tissue therapysystem, as well as methods of using the systems and devices, aredescribed in U.S. patent application Ser. No. 12/372,661, filed on Feb.17, 2009, which is hereby incorporated by reference in its entirety.

Upon removal of the activation tool 190, the springs 195 are able toexert a proximally directed force onto the sliding seal assembly 160,which is capable of generating reduced pressure in the suction chamber110 and transmitting the reduced pressure to a sealed wound enclosurecoupled to the device 100. The reduced pressure is generated byexpanding the volume of air initially located in a sealed enclosure orchamber of the device from a smaller volume of the chamber to a largervolume. Upon expansion of the air within the sealed enclosure, thedensity of the air molecules is decreased and the pressure within thesealed chamber is reduced to a sub-atmospheric level. As exudates and/orgaseous leakage occurs, the springs 195 will retract the sliding sealassembly 160, thereby maintaining the reduced pressure level within thecollection chamber. In some variations, there may be a lubricantprovided between the sliding seal assembly 160 and the internal walls ofthe suction chamber 110, which may help the sliding seal assembly tomove smoothly and consistently across the suction chamber to generatenegative pressure. As the sliding seal assembly 160 returns to itsmaximum retracted state, the level of reduced pressure level will beginto decrease and may be replaced or recharged.

FIGS. 1C and 1D are superior and side elevational views of the devicefrom FIG. 1A in an activated state and with the springs 195 havingpartially expended the potential energy from the fully chargedconfiguration. As can be seen when the sliding seal assembly 160 is in apartially expended position, the suction chamber 110 may be subdividedby the sliding seal assembly 160 into a collection chamber 162 and aworking chamber 164, where the collection chamber 162 is the spacebetween the sliding seal assembly 160 and the distal end wall 112 of thesuction chamber 110, and the working chamber 164 is the space betweenthe proximal end 114 of the suction chamber 110 and the sliding sealassembly 160 which contain the springs 195. When the suction device isin the charged configuration, the volume of the collection chamber maybe about zero, or sometimes less than about 5 cc. In some instances,upon activation of the mechanically charged device, the collectionchamber may increase in volume up to about 3%, sometimes about 5% andother times about 10% or even about 20% until the force exerted by thesprings 195 is counterbalanced by the force generated by the reducedpressure in the collection chamber 162. In some variations, a suctiondevice may be configured to apply a pre-determined amount of negativepressure. For example, the volume of the suction chamber and/or thespring constant of constant force springs may be selected in order toprovide a pre-determined amount of pressure. Pre-determined pressurelevels may range from −50 mmHg to −150 mmHg, e.g., −75 mmHg, −100 mmHg,−125 mmHg, etc.

Some variations of a reduced pressure therapy system may be configuredto remove and store exudates located at the treatment site. Exudates aretypically body fluids or mixed fluids and other cellular matter. In somevariations, the device may be configured with a fluid retentionmechanism to resist or prevent leakage of the exudates that have beensuctioned into the suction chamber. For example, some fluid retentionmechanisms may be configured to sequester exudates within a certainportion of the suction device, regardless of the orientation of thesuction device. This may help to reduce the risk of contamination tousers or healthcare personnel and their surroundings during use and/ordisposal. In some variations, the fluid retention mechanism may beconfigured to prevent exudates that have been drawn into the suctiondevice from flowing out of the suction device. For example, a fluidretention mechanism may be configured to allow exudates to flow in onedirection (e.g., into the suction device), but not in the oppositedirection (e.g., out of the suction device). In some variations, asuction device may have a fluid retention assembly in its suctionchamber, where the fluid retention assembly may comprise an absorbentmaterial so that when the exudates come into contact with the absorbentmaterial, it is absorbed by the material and retained and/or sequesteredwithin the suction chamber. Optionally, the fluid retention assembly mayalso comprise a screen or mesh that may be used to sequester theabsorbent material in a certain portion of the suction chamber. Thescreen or mesh may also help to prevent the absorbent material frommoving around and/or exiting the suction chamber, and in somevariations, may also help to prevent exudates collected in the suctionchamber from exiting the chamber through the distal port or inlet.

Absorbent materials that may be used in a fluid retention assembly maybe selected according to the expected viscosity (or other liquidcharacteristic) and/or quantity of the exudates. Certain absorbentmaterials may also be selected based on the desired absorption capacity.The absorption capacity of the material may be maintained under negativeand/or positive pressure conditions. Some variations of an absorptionmaterial may hygroscopic, and may be able to absorb vapor. The fluidabsorption material may be permeable to air, such that the negativepressure generated by the suction device may be conveyed to the woundwithout substantial hindrance. Suitable absorbent materials may beselected from natural, synthetic, and modified natural polymers andmaterials. Absorbent materials may be inorganic or organic materials,such as sodium acrylic-based polymers, silica gels, cross-linkedpolymers, etc. Other examples of absorbent materials may include gauze,pulp, sponges, foams, desiccated hydrogels, and cross-linked polyproticresins. Suitable absorbent materials may be available from variouscommercial vendors, such as Dow Chemical Company located in Midland,Mich., U.S.A., and Stockhausen GmbH & Co. KG, D-47805 Krefeld, FederalRepublic of Germany. Other examples of absorbent materials may includestarch-acrylonitrile co-polymers, carboxy methyl cellulose (CMC),acrylic acid, polyvinyl alcohol (PVA) and isobutylene maleic anhydride(IMA), as well as various foams, including XTRASORB™. Some variations ofa fluid retention assembly may use a superabsorbent material, which maybe capable of retaining an amount of water equal to at least 100% of itsdry weight (e.g., as measured by the test of Intrinsic AbsorbentCapacity). In some of the foregoing embodiments, the superabsorbentmaterial may be Isolyser™ by Microtek Medical. Other examples ofabsorbent materials that may be used with a fluid retention assembly fora suction device may include sodium polyacrylate with sodiumdichloro-S-triazinetrione dihydrate, cellulose based substrates, AQUAKEEP® polymer products, etc.

In some variations, the fluid absorbent material may have a firstnon-hydrated state and a second hydrated state, where in thenon-hydrated state the absorbent material may occupy a smaller volumethan when in the hydrated state. For example, the absorbent material mayexpand as it absorbs fluids and transitions from the non-hydrated tohydrated configuration. In some variations, the absorbent material inthe non-hydrated state may be powder-like, and in the hydrated state,the absorbent material may be gel-like, or may be a solid or asemi-solid. In other variations, the absorbent material may be a planarsheet or pad that thickens or expands as it absorbs fluid. The fluidabsorbent material may be a porous material (e.g. a sponge, foam,textile, etc), and may be a planar or three dimensional porous matrix.An absorbent material that is a planar pad may have a first thickness inthe non-hydrated state, and a second thickness in the hydrated state,where the second thickness is greater than the first thickness.Alternatively or additionally, the absorbent material may comprise loosecomponents such as pellets, spheres, granules, clusters, powder, and thelike. The particle sizes may range from about 20 μm to about 500 μm, forexample, about 20 μm to 30 μm, or about 200 μm to 300 μm, or about 350μm to 390 μm in the non-hydrated state. The absorbent material may alsotake the form of a collapsed woven material, such as a textile, orcompressed polymer or sponge or porous matrix in its non-hydrated state.In the expanded hydrated state, the absorbent material may expand, andmay be enlarged pellets or clusters, an expanded textile or sponge orporous matrix. In some cases, the absorbent material in the hydratedstate may be a solid, a semi-solid, or a gel. Some variations ofabsorbent materials may decompose as it absorbs fluids. In someexamples, the fluid absorbent material may be a volume neutral material,wherein the total volume of the separate fluid and separate absorbentmaterial is approximately the same volume of the fluid and absorbentmaterial when intermixed. For example, the separated total volumes andthe intermixed volume may be equal, or at least within 5% or 10% of eachother. In other examples, the fluid absorbent material may be a volumeincreasing material, wherein the intermixed volume is at least 15% or25% or more than the total separated volumes.

The amount of absorbent material that is provided in the suction chambermay be limited by the dimensions of the collection chamber of a chargedsuction device. In some embodiments, the absorbent material may occupy avolume of less than about 10 cc, about 5 cc or about 4 cc. In otherembodiments, the volume of the absorbent material may be characterizedby the maximum volume of the chamber in which it resides. For example,the absorbent material may less than about 25%, about 20%, about 15%, orabout 10% of the chamber volume. In some embodiments, the amount ofabsorbent material may be between 0.5 g to 4 g. In some embodiments, theamount of absorbent material may be between 0.5 g to 2.5 g. In someembodiments, the amount of absorbent material may be between 0.5 g to1.75 g. In some embodiments, the amount of absorbent material may beabout 1.5 g. In some embodiments, the amount of absorbent material maybe at least 1 g. In some embodiments, the amount of absorbent materialmay be at most 2 g. In some embodiments, the amount of absorbentmaterial may be at most 3 g. In some embodiments, the amount ofabsorbent material may be at most 4 g.

Optionally, some variations of a fluid retention assembly may comprise adisinfectant, which may help to sanitize exudates that enter thecollection chamber. For example, the disinfectant may be attached to,bonded to, embedded in, cross-linked with and/or otherwise incorporatedwith the absorbent material. In other examples, the disinfectant may befreely disposed within the collection chamber, or may be attached toother structures, such as the slidable seal assembly. The disinfectantmay be anti-bacterial (e.g. bacteriostatic or bacteriocidal),anti-viral, anti-fungal, and/or anti-parasitic. Some examples ofdisinfectant compounds that may be used in a fluid retention system mayinclude chlorhexidine, sodium hypochlorite, sodiumdichloro-s-triazinetrione dehydrate (or other chlorine-baseddisinfectant), a sulfonamide, silver sulfadiazine, polyhexanide. In somevariations, the absorbent material itself may also act as adisinfectant. For example, a fluid retention assembly may use a liquidmedical waste solidifier, such as Isolyser LTS-Plus® Solidifier orIsosorb® Solidifier by Microtek Medical. Optionally, the fluid retentionassembly may also comprise a deodorizer, such as zeolite, activatedcharcoal, silica gel, or hydrogen peroxide. In some variations, thedisinfectant treat the collected exudates such that the expended devicemay be disposed as regular trash, rather than as biohazardous waste.

A fluid retention assembly may be installed in the suction chamber of asuction device in a variety of configurations. Fluid retentionassemblies may comprise an absorbent material that may be sequestered ina portion of the suction chamber, temporarily or permanently. Forexample, a fluid retention assembly may comprise an absorbent pad orsheet that may be attached to the walls of the suction chamber so thatit does not move within the suction chamber as the suction devicechanges orientation. Alternatively or additionally, a fluid retentionassembly may comprise a screen (e.g., a mesh, filter, etc.) that may beattached at a distal portion of the suction chamber. For example, thescreen may be attached within the distal portion of the suction chamber,just proximal to a distal portion leading to the distal port of thesuction device. In some fluid retention assemblies, the absorbentmaterial may be retained by a carrier structure, e.g. bonded to asurface of a supporting sheet or other structure, or enclosed in a pouchor other container. The pouch may freely move within the suctionchamber, or may be attached to any desired region of suction chambersuch that it remains at the desired region despite any changes in theorientation of the suction device. A fluid retention assembly maycomprise a combination of one or more of the above described components,as may be desirable. For example, a fluid retention assembly maycomprise absorbent materials enclosed in a pouch, where the pouch issequestered to a portion of the suction chamber by one or more screens.A fluid retention assembly may comprise an absorbent pad or sheet thatmay be temporarily or permanently secured within the suction chamberusing adhesives and/or one or more screens. Various examples of fluidretention assemblies are described below.

In some variations, the absorbent material of a fluid retention assemblymay be retained by a carrier structure, such as a pouch. In somevariations, the absorbent material may be enclosed in an internal pouchmade of a semi-permeable membrane. This internal pouch may help toprevent the fluid absorption material from obstructing or clogging thevarious valve and/or conduits of the suction device. A pouch 1804 may betemporarily or permanently attached to any portion of the suctiondevice, for example, in a distal portion of a suction chamber 1800(toward the distal port 1802), as depicted in FIG. 18A. In somevariations, the pouch may be located adjacent to the internal opening ofthe distal port 1802. The absorbent material may be surrounded by andenclosed in a liquid permeable membrane to form an absorbent bag. Themembrane may be a mesh, filter, screen, molecular sieve, and the like.Non-limiting examples of suitable materials for the liquid permeablemembrane may include woven and nonwoven polyester, polypropylene, nylon,rayon or the like, particularly in the form of formed or aperturedthermoplastic films, including those described in U.S. Pat. No.4,324,246 issued to Mullane and Smith on Apr. 13, 1982 and U.S. Pat. No.4,342,314 issued to Radel and Thompson on Aug. 3, 1982. Other knownsemi-permeable membrane materials can be employed, including those madefrom textured cellulosic basesheets with hydrophobic matter added toselected portions of the basesheet, particularly the most elevatedportions of the basesheet, as described in commonly owned copending U.S.application, “Dual-zoned Absorbent Webs”, Ser. No. 08/997,287, filedDec. 22, 1997. In some of the foregoing embodiments, an outer surface ofthe liquid permeable membrane may be treated with a surfactant toimprove liquid penetration, and may have gradients in wettabilitycreated having different chemical treatments on the two surfaces of thetopsheet, such that fluid is preferentially absorbed in targeted intakeregions and repelled by other regions. In some of the foregoingembodiments, the liquid permeable membrane may comprise at least oneseam wherein at least two sections of the membrane are joined together.In some embodiments, the expansion of the absorbent material within theliquid permeable membrane may result in the rupture of theliquid-permeable membrane. In certain embodiments, the absorbentmaterial may be expelled upon rupture of at least one seam of theliquid-permeable membrane.

In some of the foregoing embodiments, a semi-permeable membrane of afluid retention assembly may contain the absorbent material and help toisolate the material from contacting the suction device. Thesemi-permeable membrane may allow fluids to cross the membrane in onedirection, but not in the other direction. For example, a semi-permeablemembrane pouch containing absorbent material inside may allow exudatesto be drawn by the absorbent material into the pouch, while thesemi-permeable membrane prevents the exudates from flowing out of thepouch. The membrane may be permeable to air, as may be desirable. Insome variations, a fluid retention assembly may comprise a pouch made ofa fluid impermeable material that is directly connected to the distalportion of the suction device. Negative pressure may be generated in thepouch and conveyed to the tissue site. Any exudates collected by thepouch during negative pressure therapy may be retained such thatexudates do not contact the walls of the suction chamber. When thesuction device is depleted, the pouch may be removed from the suctiondevice and discarded.

Optionally, some variations of a fluid retention assembly may comprise ascreen or mesh positioned near the distal end of the suction chamber toretain the absorption material within a certain region of the suctiondevice. The screen or mesh may prevent or resist the extrusion orrelease of the absorbent material from the suction chamber, which mayoccur during patient movement and/or recharging of the device. Forexample, a screen or mesh may be semi-permeable, which may allowexudates to be collected in a suction chamber, but may prevent theexudates from exiting the distal port of the suction chamber. In somevariations, the screen or mesh may be air and fluid permeable, but notfluid absorbent. FIG. 18B schematically depicts a suction chamber 1800with a distal port 1802, and a screen 1806 proximal to the distal port1802. In some variations, a fluid retention assembly may comprise aplurality of screens or meshes, arranged such that the absorbentmaterial is constrained between two screens. In some variations, thescreen or mesh may block movement of particles of a certain size and/orliquid or semi-solid of a certain viscosity, while allowing smallerparticles and liquids to pass therethrough. The screen or mesh may beprovided over the distal portion of the suction chamber, for example,the screen may be attached over a distal valve of the suction deviceleading to the tissue treatment area. Suction devices that use anabsorbent material that has discrete components in its non-hydratedstate, such as powder, pellets, loosely associated particles, may havesuch a screen or mesh to help prevent the material from exiting thesuction chamber.

The screen or mesh may have a sieve size large enough to permit thefluid exchange of liquid and air through the mesh, but small enough tonot allow solids or semi-solids to pass through. The mesh may have twosides, a proximal and a distal side. The proximal side faces the slidingseal assembly while the distal side faces the distal end of the chamber.In some embodiments, the sieve size of the mesh may be less than 5 mm.In some embodiments, the sieve size of the mesh may be less than 2 mm.In some embodiments, the sieve size of the mesh may be less than 1 mm.In some embodiments, the sieve size of the mesh may be less than 0.5 mm.In some embodiments, the sieve size of the mesh may be less than 10 mm.The mesh may comprise any of a variety of materials, including a metal(e.g. steel, copper), a ceramic, or a plastic (e.g. polypropylene,polyethylene, polyester, polyamide or other thermoplastic.

Some fluid retention assemblies may use a screen or mesh made of a wovenor a fibrous material. For example, the screen may be made fromrandom-laid fibers (e.g., from wood pulp) using water or air to transferthe fibers. After the fibers have been air or liquid laid, syntheticresin bonding agents may be applied to the pulp web using a sprayprocess. Meshes that may be used in a fluid retention assembly may bemade of Airtex® airlaid fabrics, which may be obtained fromGeorgia-Pacific (Neenah, Wis.).

Other variations of fluid retention assemblies may comprise an absorbentmaterial that has a self-contained form (e.g., a porous matrix, sponge,gauze, pad, foam, etc.). The absorbent material may be permeable to air,as may be desirable. In some examples, the absorbent material may bewoven or non-woven sponges or gauze, and/or may be made of a porousmaterial. In some variations, the absorbent material may be permeable toair, as may be desirable. The absorbent material may be made of any ofthe materials previously described. In some variations, the absorbentmaterial may be retained by a carrier structure. For example, theabsorbent material may be immobilized in a substrate (e.g., impregnatedor woven into a matrix, adsorbed to a porous matrix, etc.). In somevariations, the absorbent material may be bonded to the carrierstructure and/or integrated with the substrate matrix. The absorbentmaterial may or may not be sterile. Fluid retention assembliescomprising such absorbent materials may or may not include a screen ormesh to prevent movement of the absorbent material as the suction devicechanges orientation. An absorbent material, e.g., an absorbent pad 1808,may be temporarily or permanently attached at any desirable portion ofthe suction device, for example, at a distal portion of the suctionchamber 1800, as depicted in FIG. 18C. The self-contained absorbentmaterial may be retained in the suction chamber by adhesion, frictionfit, and the like, and/or may conform to the cross-sectional geometry ofthe suction chamber (e.g., form fit).

Fluid retention assemblies may comprise any combination of the featuresdescribed above. For example, a fluid retention assembly may comprise ascreen 1812 attached at a distal portion of the suction chamber 1800(e.g., covering the distal port 1802) and a pouch 1810 comprising anabsorbent material enclosed in a semi-permeable membrane, as depicted inFIG. 18D. The screen 1812 may have a smaller cross-sectional area thanthat of the suction chamber 1800. In other variations, a fluid retentionassembly may comprise a screen 1816 attached at a distal portion of thesuction chamber 1800 just proximal to the distal port 1802 and a porousmatrix 1814 attached to the walls of the suction chamber 1800, justproximal to the screen, as illustrated in FIG. 18E. The screen 1816 mayhave a similarly sized cross-sectional area as compared to the suctionchamber 1800. In still other variations, a fluid retention assembly maycomprise a porous matrix attached to the side walls of the suctionchamber at a distal portion of the chamber, and a pouch comprising anabsorbent material enclosed in a semi-permeable membrane proximal to theporous matrix. Alternatively, the porous matrix may be located proximalto the absorbent pouch. The components of the fluid retention assembliesdescribed here may be arranged in any order, as may be suitable (e.g.,the pouch or porous matrix may be distal to the screen). While retentionassemblies comprising a single screen or filter have been describedhere, in some variations, there may be more than one screen. Additionalscreens may be helpful for sequestering the absorbent material in one ormore selected regions of the suction chamber, and may provide foradditional filtration of exudates, as may be desired.

One example of a suction device with a fluid retention assembly isdepicted in FIGS. 16A and 16B. Suction device 1600 may have a fluidretention assembly comprising a pouch 1602 configured to retain a fluidabsorbent material, an air and liquid-permeable screen or mesh 1604between the pouch 1602 and a distal port 1607, and optionally one ormore adhesive tabs 1606 to attach the pouch 1602 to the mesh, and/or toattach the mesh 1604 to the distal portion of the suction chamber 1605.The pouch 1602 may comprise a semi-permeable membrane (e.g., an air andliquid permeable membrane) so that the absorbent material in the pouchmay draw exudates into the pouch. In some variations, the semi-permeablemembrane may be configured to help reduce leakage of exudates out of thepouch. The absorbent material in the pouch may be any of the materialspreviously described. The pouch and mesh may or may not have a shapethat corresponds to the cross-sectional shape of the suction device(e.g., the cross-section of the suction chamber). FIG. 16B depicts anenlarged view of the pouch 1602, which has an elliptical shapecorresponding to the elliptical shape of the suction chamber 1605. Thepouch 1602 may comprise a sealed opening, or a perimeter seal 1603between two layers of the pouch, which may help to retain the fluidabsorbent material in the pouch prior to use. In some variations, uponabsorption of a sufficient amount of fluid into the pouch, the sealedopening or the perimeter seal 1603 may be configured to open orseparate, permitting expansion and/or release of the fluid absorptionmaterial into the rest of the suction chamber. In some other variations,the sealed opening or the perimeter seal 1603 may also be used to helptemporarily or permanently secure the pouch 1602 to a location in thesuction chamber, e.g., the proximal or distal side, so that the pouch1602 does not move within the suction device chamber. Optionally, thefluid retention assembly may comprise additional meshes, which may beused to secure the pouch and/or to filter exudates. For example, anadditional mesh may be provided on other proximal side of pouch 1602,across from the mesh 1604, where the two meshes may act to retain thepouch 1602 between them. Additional descriptions of suction devices andfluid absorption materials that may be used within a suction device areprovided in U.S. Pat. Appl. No. 61/372,837, filed on Aug. 11, 2010,which is hereby incorporated by reference in its entirety. In some ofthe foregoing embodiments the pouch may be placed in the suction chamberin contact with the proximal side of the mesh in a way that permits airand liquid to fluidly exchange from one side of the mesh to the other.

Another example of a fluid retention assembly 1700 is depicted in FIGS.17A-17C. The fluid retention assembly 1700 may comprise an absorbent pad1702 at a proximal location, a first adhesive layer 1704, a mesh orscreen 1706, and a second adhesive layer 1708 at a distal location. Theabsorbent pad may be made of any of the absorbent materials describedpreviously. The fluid retention assembly 1700 may be located towards adistal portion of the suction device, such that the absorbent pad 1702faces the suction chamber, and the second adhesive layer faces thedistal-most portion of the suction device. For example, the fluidretention assembly 1700 may be placed at a distal portion of the suctionchamber, over the internal aperture of the distal port of the suctiondevice. The first and second adhesive layers 1704, 1708 may be made ofany suitable adhesive, such as pressure sensitive adhesives, and mayhave adhesive properties on both sides. The first adhesive layer 1704may be used to attach the absorbent pad 1702 to the screen 1706. Thesecond adhesive layer 1706 may be used to attach the screen 1706 to adistal surface of the suction device. As depicted in the side view ofFIG. 17B, the second adhesive layer 1708 may optionally have anadditional release liner layer 1707, which may allow the fluid retentionassembly 1700 to be manufactured separately from the suction device, andthen subsequently attached to the device prior to use. The screen 1706may be made from any air or liquid permeable material, such as thescreen materials described above.

The second adhesive layer 1708 may have an aperture 1709 (and the firstadhesive layer 1704 may have a corresponding aperture which is notshown). In some variations, the aperture 1709 may facilitate the flow ofsuction through the fluid retention assembly 1700. In other variations,one or more adhesive structures or regions may be provided that need notattach the entire distal surface or entire perimeter of the fluidretention assembly to the suction chamber. The one or more adhesivestructures may or may not be located over an opening of the suctionchamber. As depicted in FIG. 17C, the absorbent pad 1702 may also havean aperture 1710 that is aligned with the adhesive layer aperture 1709.As shown in FIG. 17D, the screen 1706 may not have an aperture, andtherefore, the screen 1706 spans across the adhesive and absorbent padapertures 1709, 1710. However, since the screen may be made of an airand liquid permeable material, the negative pressure generated in thesuction chamber may be conveyed to a distal wound bed. The mesh size ofthe screen 1706 may be selected such that particles larger than the meshsize may not pass between the wound and the suction chamber. Forexample, wound exudates with blood material that is substantially liquidmay pass from the wound to the suction chamber, but after the blood hasclotted in the suction chamber, it cannot pass from the chamber back tothe wound bed. Optionally, one or more additional screens may beprovided to provide additional filtration of exudates and/or to securethe absorbent pad 1702, as may be desirable. For example, an additionalscreen may be provided on a proximal side of the absorbent pad 1702,thereby retaining the absorbent between the additional screen and thescreen 1706. Other variations of a fluid retention assembly may not haveany screens, which may allow for the exchange of materials between thewound bed and the suction chamber.

Some variations of suction devices may comprise one or more indicatorsto inform a patient and/or practitioner when the device needs to bereplaced (e.g., when the suction device is in a depleted state and nolonger able to generate negative pressure). Visual indicators may beprovided to indicate the state of the suction device, i.e., fullycharged, at least partially charged or depleted, or fully depleted.Visual indicators may allow the position of the sliding seal assemblywithin the suction chamber to be readily identified. For example, thesuction device may display a certain color to indicate that it is fullycharged or at least partially charged or partially depleted, and adifferent color to indicate that it is fully depleted. In one variation,the sliding seal assembly may have a first portion that is coloredgreen, and a second portion that is colored red. The suction chamber maycomprise opaque and transparent portions that reveal certain portions ofthe sliding seal assembly as the suction device generates negativepressure. In some variations, the suction chamber may comprise an opaquematerial with one or more translucent or optically clear windows thatmay be used to view the location and/or colors of the sliding sealassembly within the suction chamber. For example, when the suctiondevice is fully or partially charged, the green portion of the slidingseal assembly may be visible in an optically clear window, while the redportion is obscured by the opaque portion of the suction chamber. Thegreen portion of the sliding seal assembly may allow a patient and/orpractitioner to readily determine the depletion state of the suctiondevice based on the location of the sliding seal assembly in the suctionchamber. When the suction device is depleted and no longer able togenerate any negative pressure, the red portion of the sliding sealassembly may become visible while the green portion may be obscured. Inother variations, the sliding seal assembly may have additional colorsto indicate intermediate levels of depletion. For example, the slidingseal assembly may have a first green portion, a second red portion, anda third yellow portion. The suction chamber may comprise opaque andtransparent portions that reveal only the green portion of the slidingseal when the suction device is fully charged, only the yellow portionwhen the suction device is partially charged or partially depleted, andonly the red portion when the suction device is fully depleted.Alternatively, the sliding seal assembly may have a single color orpattern that is readily visible through the suction chamber (e.g.,having bright intensity, high contrast, highly noticeable visualattributes including contrasting edges, patterns, stripes, etc.). Insome variations, the sliding seal assembly may have arrows or othersymbols that may be used in combination with indicia on the suctionchamber to indicate capacity of the device to generate negativepressure. Examples of suction devices with such visual indicators aredescribed below.

Additionally or alternatively, certain variations of a suction devicemay comprise an alarm system to inform a patient and/or practitionerwhen the device needs to be recharged or replaced. For example, an alarmsystem may generate an alert to inform a patient and/or practitionerthat a suction device is exhausted or nearly exhausted of its ability toprovide negative pressure to a wound, and may prompt the patient torecharge the device, empty or replace the collection chamber, and/orreplace the suction device. Once the suction device has been recharged,emptied, or replaced, the alert generated by the alarm system may bedeactivated and/or reset. An alarm system may also provide confirmationto the patient and/or practitioner that the suction device has beenproperly initialized or charged.

In some examples, the alarm systems for use with a suction device maycomprise a sensor mechanism and a notification mechanism. The sensormechanism may directly or indirectly detect the capability of a suctiondevice to continue to provide negative pressure, and may signal thenotification mechanism to generate an alarm. For example, an alarmsystem may directly measure the pressure that is applied to the wound,while other sensor mechanisms detect indirect device configurations thatare related to the pressure that is applied to the wound. Examples ofsensor mechanisms that directly measure the pressure applied to thewound, and/or directly measure the capability of the suction device toprovide negative pressure may include pressure transducers or gauges.Examples of sensor mechanisms that indirectly measure the pressureapplied to the wound may include position detectors, proximitydetectors, or mechanisms that are otherwise sensitive or responsive tothe location of a slidable seal of the suction device. These mayinclude, for example, linear encoders, rotary encoders, liquid sensors,volume sensors, and movement sensors, and the like. Some variations ofsensor mechanisms may be configured to detect the configuration of thesuction generating mechanism. For example, sensors may be used tomeasure the tension and/or coil state of the constant force springs of asuction mechanism. In some variations, sensor mechanisms may provide abinary output, i.e., indicating that the suction device is eithercharged or depleted, while in other variations, sensor mechanisms mayprovide a graded output, i.e., indicating that the suction device is100%, 80%, 50%, 30%, 10%, 0%, charged or depleted. Examples of binarytype sensor mechanisms may include a variety of switches, such aselectrical or magnetic switches. Examples of graded type sensormechanisms may include various encoders, such as linear or rotaryencoders.

One or more types of notification mechanisms may be used in an alarmsystem for use with a suction device. Notification mechanisms maycomprise visual alerts, audio alerts, electronic alerts, and/or tactilealerts. Examples of notification mechanisms may include LED activation,buzzers, tones, e-mail messages, text messages, vibratory mechanisms,etc. An alarm system may comprise a plurality of sensors, which may eachdrive one or more notification mechanisms. For example, an alarm systemmay comprise a first sensor to detect that the suction device isproperly charged, where the first sensor is configured to trigger afirst notification mechanism, e.g., LED activation. The alarm system maycomprise a second sensor to detect that the suction device is depleted(or depleted beyond a pre-determined threshold), where the second sensoris configured to trigger a second notification mechanism, e.g., abuzzer. An alarm system may comprise any number of sensor mechanismsand/or notification mechanism as may be desirable to inform a patientand/or practitioner of the use and configuration of the suction device.

The components of an alarm system may be located on one or morecomponents of a suction device, e.g. on the suction device, and/or maybe located on a strap, clip or housing of an attachment device that maybe used to attach the suction device to the patient. The location(s) ofthe alarm system components on the suction device and/or attachmentdevice may be selected such that the components work in combination whenthe suction device is coupled to the attachment device. The alarm systemmay be integrated with the suction device and attachment device, or maybe detachably coupled to the suction and attachment devices. In somecases, the location of the alarm system components may be determined inpart by the location of the alarm system power source, as well as by thefrequency with which the suction device or the attachment clip arereplaced. For example, if the suction device is replaced more frequentlythan the attachment device, then it may be desirable for the reusablecomponents of the alarm system (e.g., notification mechanism, sensormechanism, battery pack, etc.) to be located on the attachment device.An alarm device may comprise an attachment device with an alarm system.Any alarm system components that may come in contact with body fluidsmay also be separated from the other components to prevent contaminationof the other components. For example, portions of the sensor mechanismmay contact exudates collected in the suction chamber, and may besegregated and/or detachable from the notification mechanism. In somevariations, portions of both the sensor and the notification mechanismsmay be located on the suction device and the attachment device. Forexample, alert component(s) of the notification mechanism may be locatedon the attachment device while a trigger component of the notificationmechanism may be located on the suction device, where the triggercomponent activates the alert component when the suction device attainsa certain configuration. In some variations, the sensor and/ornotification mechanisms of an alarm system may be detachably coupled tothe suction device and/or attachment device. This may allow the alarmsystem to be removed after the suction device is depleted. The alarmsystem may then be used with a new suction device (e.g., a chargedsuction device). The configuration of the alarm system and itsarrangement with respect to the suction device and/or attachment devicemay be varied according to the needs of the patient and/or thepractitioner.

Examples of alarm system mechanisms that may be used with a suctiondevice for reduced pressure wound therapy are described below. While thecomponents of the alarm system may be described in certain locations andconfigurations, it should be understood that the components may be inalternate locations and configurations as desired.

Some variations of alarm systems may comprise a magnetic sensor that isable to detect the position and/or location of a magnetic component. Amagnetic component may itself generate a magnetic field, and/or may beany material that is capable of causing a detectable flux in a magneticfield (e.g., a wire carrying a changing an electric current), and/or maybe any material that responds to the presence of a magnetic field (e.g.,a ferromagnetic material). The movement and/or location of a magneticcomponent may activate a sensor by causing a potential difference in thesensor, which is known as the Hall effect. Magnetic sensors may compriseHall effect detection elements that measure the potential differencecaused by a moving magnet to determine the position of the magnet. Thepotential difference may indicate the precise location of the magnetwith respect to the location of the magnetic sensor. One or morecomponents of a suction device may comprise a magnetic component, andthe position and/or location of the magnetic component may be detectedby a magnetic sensor on the suction device or an alarm device. Forexample, a sliding seal assembly of a suction device may comprise amagnetic component, and a magnetic sensor on the alarm device maydetermine the location of the sliding seal assembly by detecting thelocation of the magnetic component. Alternatively, an alarm device maycomprise one or more magnetic components at certain locations and thesuction device may comprise a magnetic sensor. For example, an alarmdevice may comprise a magnetic component (e.g., along or embedded in anattachment clip or side wall), and a sliding seal assembly of a suctiondevice may comprise a magnetic sensor. As the sliding seal assemblymoves along the suction device, the sensor detects the location of thesliding seal assembly with respect to the magnetic components in alarmdevice. The position of the magnetic component relative to the sensormay be determined based on the magnetic characteristics of the magneticcomponent and a measured potential difference in a sensor caused by themovement of that magnetic component. The sensor voltage may be amplifiedand activate a notification mechanism on the alarm device to generate analarm that informs the patient and/or practitioner of the status of thesuction device. In some variations, the notification mechanism maycomprise a thresholding function that converts an output from a gradedtype sensor into a binary alert, e.g., generating an alert only when thedevice is depleted past a certain threshold.

One variation of a suction device 200 with an alarm system using amagnetic sensor mechanism is depicted in FIGS. 2A-2C. The suction device200 is configured to be retained by an alarm device comprising a clip210 and a strap (not shown). As depicted in FIG. 2B, the sliding seal202 of the suction device 200 may comprise a magnetic material 204. Oneor more magnetic sensors 206 and 208 may be provided to detect thelocation of the sliding seal 202 using the magnetic material 204. Thelocation of the magnetic sensors 206 and 208 may be configured tofacilitate detection of one or more states. For example, as illustratedin FIG. 2B, the first magnetic sensor 206 may be located at a proximalportion 207 of the clip 210 to detect when the sliding seal 202 is in aretracted position, which is indicative of the exhaustion or nearexhaustion of the suction device 200. Another sensor 208 may be locatedin a distal portion 205 of the clip 210, for example, to detect that thesliding seal 202 has been adequately displaced by the activation tool,e.g., during the mechanical charging process. The magnetic sensors 206,208 may be configured to detect the presence of absence of the magneticmaterial 204, and may be configured to provide a binary output toindicate the position of the magnetic material. Alternatively, themagnetic sensors 206, 208 may be configured to detect the proximity ofthe magnetic material 204, and may be configured to provide a gradedoutput to indicate the position and proximity of the magnetic materialto the sensors. The power source for the magnetic sensors 206, 208 maybe a battery embedded within the clip 210.

Optionally, the suction device 200 may comprise a visual indicator suchthat a patient and/or practitioner can determine the depletion state ofthe suction device by visual inspection. For example, the sliding seal202 may have a first region that is colored green and a second portionthat is colored red. As illustrated in FIG. 2A, the suction chamber 220of the suction device 200 may comprise an opaque portion 222, a firsttransparent portion 224, and a second transparent portion 226. The firsttransparent portion 224 may extend longitudinally from a distal portionto a proximal portion along the suction chamber 220. The width of thefirst transparent portion 224 may be such that the green region of thesliding seal 202 is exposed, while the red region of the sliding seal isobscured by the opaque portion 222. As the sliding seal 202 moves from adistal portion to a proximal portion of the suction chamber 220 (i.e.,as the suction device transitions from a fully charged or partiallycharged state to a depleted state), the location of the green region asseen along the first transparent portion 224 may indicate the degree towhich the suction device is depleted. When the suction device 200 isfully depleted, the sliding seal 202 may be co-localized with the secondtransparent portion 226, such that the red region of the sliding seal isvisible in the second transparent portion 226 while the green region ofthe sliding seal is obscured. As depicted in FIG. 2A, the firsttransparent portion 224 may be longitudinally disposed with an oblonggeometry and the second transparent portion 226 may be transverselydisposed with a curved elongated geometry. However, it should beunderstood that the transparent portions may be located anywhere on thesuction device and may have any size or shape as suitable forcooperating with the markings on the sliding seal to provide a visualindicator of the state of the suction device. Such a visual indicatormechanism may be used alone or in combination with any of the alarmsystems described herein.

The output of an indicator or sensor mechanism may be used to generatean alert. In some variations, the output voltage of a magnetic sensormay be amplified in order to drive notification mechanisms and/orcircuits. For example, the magnetic sensor may comprise a Hall effectsensing mechanism whose output voltage or current may be amplified todrive one or more notification mechanisms. Each magnetic sensor mayactivate independent notification mechanisms, and/or may signal a sharednotification mechanism. As an example, the first magnetic sensor 206 mayactivate a first notification mechanism when the magnetic component 204of the sliding seal 202 is located at or near the proximal portion 207of the clip, and the second magnetic sensor 208 may activate a secondnotification mechanism that is distinct from the first notificationmechanism when the sliding seal 202 is located at or near the proximalportion 207 of the clip. In some variations, the voltage outputs of thefirst and second magnetic sensors 206 and 208 may be inputs to a logiccircuit that computes the location of the sliding seal 202 when it isbetween the distal portion 205 and the proximal portion 207 of the clip.The result of this logic circuit may be used to activate a thirdnotification mechanism. For example, when a fully charged suction device200 is attached to the clip 210, the first notification mechanism may beactivated by the first magnetic sensor 206, and issue a first visualand/or audio alert. As the suction device 200 is used to apply negativepressure to a tissue region, the third notification mechanism may beactivated by the first and second magnetic sensors 206 and 208, andissue a second visual and/or audio alert when the sliding seal 202 ishalfway between the distal portion 205 and the proximal portion 207 ofthe clip 210. When the suction device 200 is exhausted or depleted, thesecond notification mechanism may be activated by the second magneticsensor 208, and issue a third visual and/or audio alert. Some magneticsensors may provide a binary output that indicates whether or not thesliding seal is at the location of the sensor or not, while othermagnetic sensors may provide a graded output that indicates how far awaythe sliding seal is from the sensor. In some alarm systems, a pluralityof binary type sensors may approximate the functional output of a gradedtype sensor. For example, while clip 210 is shown to have two magneticsensors, it should be understood that other variations of alarm devicesmay have any number of magnetic sensors, e.g., there may be 1, 3, 4, 5,6, 10, 12 or more magnetic sensors to detect the position of the slidingseal.

One example of a binary type sensor is a magnetic field sensitiveswitch, which may be configured to activate a notification mechanism inthe presence of a magnetic field. Such binary type magnetic fieldsensitive switches change between an open and closed configurationaccording to the proximity of magnet. One example of a magnetic fieldsensitive switch is a reed switch, which is schematically depicted inFIGS. 7A and 7B. A reed switch 700 comprises a first electrical contact702 on a first ferrous metal reed 706, and a second electrical contact708 on a second ferrous metal reed 710. In the absence of a magneticfield, e.g., when a magnet 712 is some distance away from a centralregion 701 of the reed switch 700, the ferrous metal reeds 706, 710 andthe associated electrical contacts 702, 708 may be in an openconfiguration such that the electrical contacts 702, 708 are separatedby a distance, i.e., not touching or contacting each other. In thepresence of a magnetic field, e.g., when the magnet 712 is in proximityof or within the central region 701 of the reed switch 700, the ferrousmetal reeds 706, 710 may move according to the field and cause theelectrical contacts 702, 708 to touch, thus closing the reed switch 700.In other variations, reed switches may be in a closed configuration inthe absence of a magnetic field, and transition to an open configurationin the presence of a magnetic field. While a reed switch is describedhere, other examples of binary magnetic field sensitive switches mayinclude proximity switches, speed switches, and the like. Any type ofbinary type magnetic field sensitive switches, as well as graded typemagnetic field sensitive detectors, may be used to detect the presenceof a magnet, as appropriate.

One example of a suction device 230 with an alarm system using amagnetic field sensitive switch is depicted in FIG. 8, which illustratesthe suction device 230 in a depleted configuration, e.g., just prior tocharging with a key. As depicted there, the sliding seal 232 of thesuction device comprises a magnet 234. The magnet 234 may be located onone side of the sliding seal 232 (e.g., the right side 253), but mayalso be located in the center of the sliding seal, or may extend alongthe entire length of the sliding seal, for example, similar to themagnetic component 204 depicted in FIGS. 2A to 2C. The magnet may belocated on the superior portion 250 of the sliding seal (as depicted inFIG. 8), on the inferior portion 251, and/or the left side 252 and/orright side 253 (e.g., the left or right edge) of the sliding seal. Insome variations, the magnet may be embedded within the sliding seal.Alarm device 242 may comprise one or more clips 240 for retainingsuction device 230 and a strap coupled to the one or more clips (notshown). A first reed switch 236 may be provided at any location on thealarm device 242, for example, at a location that is close to theposition of the sliding seal 232 when the suction device 230 isdepleted, e.g., at a proximal portion 237 of the clip 240. When themagnet 234 is sufficiently close to the proximal portion 237, themagnetic field from the magnet 234 may affect the first reed switch 236such that it transitions from an open configuration to a closedconfiguration. Closing the first reed switch 236 may activate any of thenotification mechanisms described below to generate an alert to indicatethat the suction device is depleted. Optionally, a second reed switch238 may be provided at a distal portion 235 of the clip 240 which may beconfigured to activate the same or different notification mechanism asthe first reed switch 236. For example, the second reed switch 238 maybe transitioned from an open configuration to a closed configurationwhen the sliding seal 232 is a distal portion of the suction device 230,which may activate a notification mechanism to indicate that the devicehas been successfully charged. In some variations, as discussed infurther detail below, a second reed switch may be provided to permit thecoupling of the suction device to the alarm device in eitherorientation. Any number of locations on the alarm device may have one ormore reed switches according to where the practitioner and/or patientdesires to be informed of the location of the sliding seal 232. Thesensitivity of the reed switch may be configured depending upon theparticular configuration of the suction device and magnetic shieldingprovided, if any, to protect other surrounding electronic devices. Insome variations, greater magnetic shielding may be provided for use inthe intensive care unit or hospital setting, or with patients withimplantable devices such as a defibrillator or pacemaker. In someexamples, non-magnetic MRI-compatible units may be provided in additionto magnetic variants of the device, and the clip may be configured withtwo or more detector mechanisms to accommodate multiple types ofdevices.

In some variations, the sliding seal 232 may comprise a second magnet233 that is located on the left side 252 of the sliding seal 232. Theadditional magnet may allow the suction device 230 to be retained in thealarm device 242 in an alternate orientation. For example, the suctiondevice 230 may be retained in the alarm device in an orientation that isrotated 180° around the longitudinal axis from the orientation depictedin FIG. 8 (e.g., such that the relative position of the superior portion250 of the suction device is interchanged with the inferior portion 251,and the left side 252 is interchanged with the right side). Suction andalarm devices with alarm systems that are configured to accommodate aplurality of retention orientations will be described in detail below.

One variation of a suction device 330 with an alarm system using agraded type magnetic sensor mechanism is depicted in FIG. 3A. Suctiondevice 330 is configured to be retained within alarm device 344, whichmay comprise a clip with a magnetic linear encoder 342 at a proximalportion 346 of the alarm device 344. Optionally, the alarm device 344may comprise a strap that may be coupled to the clip to attach it to apatient. The power source for the linear encoder 342 may be a batteryembedded within the alarm device 344. Suction device 330 comprises amulti-pole flexible magnetic strip 332 that spans along a longitudinallength of the device, from a proximal portion 334 to a distal portion336 of the device, and aligned over the magnetic linear encoder 342. Thedistal end of the flexible magnetic strip 332 may be fixedly attached tothe base of a sliding seal 338 of the suction device 330, and rotatablyattached to the proximal portion 334 of the suction device. The relativemotion due to the longitudinal shortening of the magnetic strip duringthe application of negative pressure may be detected by the magneticlinear encoder 342. In some variations, the magnetic strip 332 may becoupled to a portion of the springs 340. In the charged configuration,the magnetic strip 332 is extended, as depicted in FIG. 3A. As thesprings 340 recoil and shorten during the course of negative pressuretherapy, the magnetic strip may recoil and shorten similarly (as themagnetic strip 332 may be at least partially coiled at the proximalportion 334). In other variations, as depicted in FIG. 3A, the magneticstrip 332 may be coupled to a non-central region of the sliding seal338, and as the suction device 330 is used to apply negative pressure,the magnetic strip 332 shorten and form a coil around a rotatable pinthat is separate from the coil of the springs 340. Alternatively oradditionally, the magnetic strip 332 may be wrapped around a firstrotatable pin at the proximal portion 334, and coupled to a secondslidable and/or rotatable pin that retains the magnetic strip within thehousing of the suction device 330. For example, the second pin may beslidable on a side slit in the housing of the suction device 330, andmay be coupled to the sliding seal 338 such that its movement across thesuction device corresponds to the movement of the sliding seal. Therotation of the pin and/or the movement of the magnetic strip 332 acrossthe magnetic linear encoder 342 may be detected and used to trigger analarm when the suction device 330 is exhausted or depleted. The secondpin may be made of a magnetically detectable material (e.g., a magnet orferromagnetic metal, etc.), which may allow its location along thesuction device to be detected by any suitable proximity detector (e.g.,any of the sensors described above).

In other variations, a multi-pole magnetic strip may be located along alongitudinal length of the clip, and the magnetic linear encoder may beembedded in the slidable seal of the suction device, in alignment withthe magnetic strip. As the slidable seal with the linear encoder movesacross the magnetic strip, the linear encoder detects the relativemovement between the seal and the magnetic strip, which may be used tocompute the location of the slidable seal within the suction device. Inthis variation, a power source such as a battery may be provided on thesuction device, where the power source may be mechanically orelectrically recharged and/or may be replaced when depleted.

Another variation of a suction device 300 with an alarm system using agraded type magnetic sensor mechanism with an alarm device 310 isillustrated in FIG. 3B. The suction device 300 comprises a shaft 302that is fixedly attached to a sliding seal 306. The shaft 302 maycomprise an elongate magnetic component 304 that may be embedded along asubstantial length of the shaft. The alarm device 310 may comprise aclip having one or more magnetic linear encoders 308 to detect themovement of the elongate magnetic component 304 embedded in the shaft302. A magnetic linear encoder located at the proximal portion 307 ofthe clip 310 may detect when the suction device 300 is depleted andtrigger a notification mechanism to generate an alert.

The elongate magnetic component 304 may be embedded over 30% to about100% of the total length of the shaft 302. The shaft 302 may have alength such that it does not protrude from the body of the suctiondevice 300. For example, the shaft length may be is less than or equalto the distance between the sliding seal 306 and the proximal portion313 of the suction device 300 in the depleted configuration. Forexample, the distance between the sliding seal 306 and the proximalportion 313 of the suction device in the depleted configuration may befrom about 30 millimeters (mm) to about 200 mm, e.g., 90 mm.Accordingly, the length of the shaft 302 may be from about 10 mm toabout 60 mm, e.g., 30 mm. Alternatively, certain suction devices mayhave a shaft with an elongate magnetic component that has a length thatmay protrude from the body of the suction device in the depletedconfiguration. Optionally, the shaft 302 may have a lumen therethroughconfigured to retain a key to mechanically charge the device.

In some variations, the elongate magnetic component 304 may be amulti-pole magnetic strip, where the pole length may be about 1.00millimeter (mm). The location of the sliding seal 306 may be determinedby the location of the elongate magnetic component 304 embedded withinthe shaft 302. The location of the elongate magnetic component may bedetected by one or more magnetic linear encoders located on an alarmdevice 310. In some variations, the magnetic linear encoders maycomprise an array of magnetic sensors, e.g., an array of Hall effectsensors.

Referring again to FIG. 3B, the alarm device 310 may have a first deviceretaining structure 314 and a second device retaining structure 316 thatis directly opposite the first device retaining structure. The alarmdevice 310 also comprises a back panel 318 that is attached to the firstand second retaining structures 314 and 316 on either side. When thesuction device 300 is retained by the alarm device 310, the shaft 302may move longitudinally across the length of the back panel 318. The oneor more magnetic linear encoders 308 may be located anywhere on thealarm device 310 such that the longitudinal axis 312 of the shaft 302passes over the linear encoder as the shaft moves. For example, in thealarm device 310 depicted in FIG. 3B, magnetic linear encoders 308 arelocated at a distal portion 305 and proximal portion 307 of the backpanel 318 that overlaps with the longitudinal axis 312. In othervariations of alarm devices, the magnetic linear encoder may be locatedanywhere on the alarm device that overlaps with the longitudinal axis ofthe suction device shaft, e.g. any location between the proximal 307 anddistal portion 305 along the longitudinal axis of the shaft.

Additionally, the location of magnetic linear encoder 308 with respectto the elongate magnetic component 304 may be determined by thespecification of the particular magnetic linear encoder selected. Forexample, the alignment of the elongate magnetic component over themagnetic linear encoder, the distance between the elongate magneticcomponent and the magnetic linear encoder, and other such positionaldetails may be described in the specification of the magnetic linearencoder selected. Examples of elongate magnetic components and magneticlinear encoders that may be used here may include the MS10-10 magneticmultipole strip (pole length 1.0 mm, 10 poles) and the AS5311 highresolution magnetic linear encoder (AustriaMicrosystems AG). Othersuitable types of magnetic components and magnetic sensors and encodersmay also be used with the suction and alarm devices described above.

While the magnetic components described above may be embedded or fixedlycoupled to the sliding seal or shaft of the suction device, in othervariations, the sliding seal or shaft may be itself magnetic, i.e., madeof magnetic materials. The sliding seal and/or shaft may comprise anintegral magnetic component, or may comprise a plurality of magneticcomponents throughout its length. Examples of magnetic materials thatmay be used in an alarm system comprising magnetic sensors include butare not limited to neodymium, iron, boron, samarium cobalt, alnico,ceramic, ferrite, various alloys (such as an alloy of neodymium, ironand boron) and the like. Alternatively or additionally, the magneticcomponents may be electromagnetic. The magnetic components may have anysize or shape as may be suitable for attaching to the suction deviceand/or alarm device. For example, the magnetic components may bemagnetic sheets or strips. Magnetic components may also be shaped as adisc, rectangular block, cylinder, etc.

The output of the magnetic linear encoder 308 may activate anotification mechanism that informs the patient and/or practitionerabout the status of the suction device 300. The notification mechanismmay be configured or programmed to issue certain indicators or alertsdepending on the positional output of the magnetic linear encoder 308.For example, the magnetic linear encoder 308 may activate thenotification mechanism to issue a first alert when the suction device300 is fully charged and installed in the alarm device 310 as depictedin FIG. 3B. When the shaft 302 has moved to a position where the suctiondevice 300 is partly depleted (e.g., about 30% depleted) the magneticlinear encoder 308 may activate the notification mechanism to issue asecond alert. Any desired number of alerts may be issued according tothe position of the shaft 302 as detected by the magnetic linear encoder308. When the shaft 302 has moved to a position where the suction device300 is nearly or fully depleted, the magnetic linear encoder 308 mayactivate the notification mechanism to issue another alert. Moregenerally, the magnetic linear encoder and the notification mechanismmay be configured or programmed to provide alerts at any frequency asdesired by the patient and/or practitioner. While an encoder thatdetects longitudinal or linear movement is described above, other typesof graded sensors will be described below.

In addition to a magnetic field sensitive reed switch described above,electrical switches that are triggered by certain configurations of thesuction device may be used to activate (e.g. by closing or opening) acircuit of a notification circuit to generate an alert. Such electricalbinary type switches may be triggered to particular configurations ofthe suction device, and may be used to activate a notificationmechanism. One variation of a suction device 400 using a binary typeelectrical switch mechanism is depicted in FIGS. 4A-4E. The suctiondevice 400 may comprise a slidable seal 420, where the slidable seal isattached or coupled to one or more springs 422 or a shaft 428 of aactivation tool 426, as previously described. Suction device 400 alsocomprises a circuit conduit 410 embedded in the slidable seal 420. Anotification mechanism as described below may be activated when theslidable seal 420 and the circuit conduit 410 are at a certain locationin the suction device. For example, when the slidable seal 420 seal isin the location depicted in FIG. 4A, the notification mechanism may notbe activated, but when the slidable seal 420 is in the location depictedin FIG. 4B, the notification mechanism may be activated.

FIGS. 4C-4E illustrate one variation of a notification mechanism thatmay be activated closing a switch when the suction device attains acertain configuration. For example, a notification mechanism may beconfigured to generate an alert when the position sensor mechanismdetects that the slidable seal is in a proximal position, i.e., thesuction device 400 is depleted or exhausted. The notification mechanismmay comprise a first activation contact 402 on one side of a proximalportion of the suction device housing 424, and a second activationcontact 403 that may be directly across from the first activationcontact. The activation contacts may extend through the entire thicknessof the housing 424. The first activation contact 402 may be electricallycoupled to the second activation contact 403 via an activation elementin the sliding seal 420, e.g., the circuit conduit 410. When the circuitconduit 410 is not aligned with both the activation contacts 402 and403, i.e., the suction device 400 is in the configuration depicted inFIG. 4A, the activation contacts are electrically isolated. When thecircuit conduit 410 is aligned with both the activation contacts 402 and403, i.e., the suction device 400 is in the configuration depicted inFIG. 4B, the activation contacts are electrically coupled, and currentmay flow between the activation contacts. There may be several pairs ofactivation contacts along the length of the suction device 400, whichmay sense various locations of the slidable seal 420 as desired. Forexample, the activation contacts 402 and 403 are located so that theymay be aligned with the circuit conduit 410 of the slidable seal 420when the suction device is depleted or exhausted. When the suctiondevice 400 is in the depleted configuration shown in FIG. 4B, theactivation contact 402, the circuit conduit 410, and the activationcontact 403 may be aligned to form an electrical pathway therebetween.

The notification mechanism may comprise a circuit configured to generatean alert. For example, the notification mechanism may comprise anotification circuit 408, where the notification circuit 408 maycomprise an open circuit which may be activated when the circuit isclosed. The notification circuit 408 may be located on an alarm device404 that is configured to retain the suction device 400, as illustratedin FIGS. 4C and 4D. The alarm device may comprise a clip, sheath, case,etc. that may have one or more grooves, protrusions, high-frictionsurfaces, etc. that are arranged to reliably retain and align thesuction device within the alarm device. The alarm device may also haveone or more bands, clips, belts, straps, etc. that may couple thesuction device to a patient, e.g., an arm or wrist band, leg strap orbrace, waist belt, and the like.

The notification circuit 408 may be attached to a back panel 428 of thealarm device 404, which is illustrated in FIG. 4E. The notificationcircuit 408 may comprise a first alarm contact 406 on one side of thealarm device, a second alarm contact 407 that may be opposite the firstalarm contact 406, and a battery (not shown). The alarm contacts 406 and407 may be the terminal nodes of an open circuit of the notificationmechanism. In the open circuit configuration depicted in FIG. 4E, thenotification circuit is in an inactivated state. Activation of thenotification circuit 408 may require an electrical conduit between thealarm contacts 406 and 407. The alarm contacts 406 and 407 may belocated such that when the suction device 400 is retained within thealarm device 404, the activation contacts 402 and 403 are aligned andtouch each other. The connection between the alarm and activationcontacts may be sufficiently intimate such that an electrical currentmay pass between them. Optionally, the engagement between the alarm andactivation contacts may help to retain the suction device 400 within thealarm device 404. In some variations, the alarm contacts and theactivation contacts may be complementary structures, such that theyengage or mate when the suction device 400 is retained by the alarmdevice 404. For example, the alarm contacts and the activation contactsmay be engaged by snap-fit, friction-fit, mechanical interfit, magneticattraction, and the like.

As described above, a notification mechanism may comprise an electricalcircuit with an open circuit where the termination nodes correspond totwo or more alarm contacts. A notification circuit may be held in aninactivated state by the open circuit, and activated when the opencircuit is closed, i.e., when one or more conductive pathways areprovided between the alarm contacts. The alarm contacts may beelectrical switch contacts and/or reed switch contacts that respond whena magnetic field is present.

In the variation of the suction device 400 described above, the alarmsystem is configured to alert the practitioner when the suction deviceis depleted of its ability to provide reduced pressure to a tissue. FIG.4B depicts the location of the slidable seal 420 when the suction deviceis nearly depleted, where the activation contacts 402 and 403 areconnected via the circuit contact 410. As described previously, when thesuction device 400 is retained in the alarm device 404, the activationcontacts 402 and 403 engage and connect with the alarm contacts 406 and407. When the suction device 400 is in the configuration shown in FIG.4B, the open circuit 432 of the notification circuit 408 is closed, andthe tone generator 434 is activated. While the open circuit 432 has beendescribed as being closed by circuit conduit 410, in other variations,the open circuit may be closed by other switch mechanisms. For example,the open circuit 432 may be closed by a spring-loaded button or knobthat may be depressed when the slidable seal attains a certain position.In some variations, the slidable seal may have a protrusion thatdepresses the spring-loaded button to close the open circuit andactivate the tone generator. As described previously, the alarm contactsof the notification circuit 408 may be closed by a reed switch. Forexample, when the magnet coupled to the slidable seal is in the vicinityof the reed switch, the reed switch may change to a closed configurationand activate the notification circuit.

The activation contacts, alarm contacts, and circuit conduit may be madeof any electrically conductive material, such as copper, gold, silver,etc. Other types of electrically conductive materials may be used in toactivate the notification circuit.

While some suction devices may comprise alarm systems with sensor and/ornotification mechanisms that track the position of the sliding sealassembly in the suction chamber of the device, alternatively oradditionally, other suction devices may comprise alarm systems thattrack other moving components, such the one or more components of thesuction generating mechanism. As described previously, a suction devicemay use one or more constant force springs to provide reduced pressureto a tissue region. The constant force springs may be extended using ashaft and/or an activation tool to push the slidable seal distally. Asthe constant force springs retract (e.g., as the ability to providereduced pressure decreases), they may form a coil in a proximal portionof the suction device. In some variations, the retraction of theconstant force springs as the suction device is depleted may rotate anaxle around which the springs are wound. When the springs retract as thesuction device is depleted, it may form a coil with increasing diameteras the springs retract. An alarm system may comprise a sensor mechanismthat is triggered by the coiling of the constant force springs. FIGS. 6Aand 6B schematically depict one example of a sensor mechanism thatdetects the coil size of a suction device spring assembly, and may beused to trigger a notification mechanism based on the degree to whichthe springs are coiled. FIG. 6A depicts the configuration of a springassembly of a suction device when the suction device is charged. FIG. 6Bdepicts the configuration of the spring assembly when the suction deviceis depleted, where a notification mechanism may be triggered to generatean alert. The spring assembly 600 comprises a first spring 602 wrappedaround a first rotatable axle 604 to form a first coil 630, and a secondspring 606 wrapped around a second rotatable axle 608 to form a secondcoil 632. The distal portions 610 of the springs are attached to aslidable seal 612. During the use of the suction device, the springsretract to apply negative pressure to a tissue site, and rotate thefirst and second rotatable axles 604, 608. A rotary encoder, which mayprovide either a binary or graded type output, may be used to measurethe rotation of the axles 604, 608 as the spring is extended orretracted, as well as the size of the coils 630, 632. Examples of howrotary encoders may be used are described below.

The rotary encoder (not shown) may measure the rotation of the axle 604and map the measured rotation of the axle 604 to a particular slidingseal location. For example, the rotary encoder may maintain an internalcount of the number of clockwise and counterclockwise rotations of theaxles 604, 608. The linear movement of the springs may be computed basedon the number of rotations in both directions. The linear movement ofthe springs may be mapped to the location of the sliding seal 612.According to the sliding seal location, the rotary encoder may generatea graded output that drives a notification mechanism, e.g., notificationcircuit 408, to generate an alert to the patient and/or practitioner.

Additionally or alternatively, the location of the sliding seal 612 maybe determined using sensors that are configured to detect the diameterof the coils 630, 632, which may vary as the suction device is used. Theconstant force spring assembly 600 may also comprise a first sensor 626and a second sensor 628, where the first and second sensors areconfigured to general a signal to the notification mechanism when thecoils 630 and 632 are sufficiently large. The first and second sensors626, 628 may be located at a distance D3 away from the respective axles604, 608, such that the sensors are not activated when the suctiondevice is charged, and activated when the suction device is depleted.For example, when the suction device using the constant force springassembly 600 is fully charged (e.g., the slidable seal is in a distalposition), the springs are fully extended as depicted in FIG. 6A, and afirst coil 630 formed by the first spring 602, and a second coil 632formed by the second spring 606 may have a diameter D1, where0.5(D1)<D3, and may be from about 0 mm to about 16 mm, e.g. D1 may befrom about 0 mm to about 30 mm, or from about 14 mm to about 17 mm, orfrom about 15.7 mm to about 15.9 mm. When the suction device is fullydepleted (e.g., the slidable seal is in a proximal portion), the springsmay be fully coiled, as depicted in FIG. 6B, and the first and secondcoils 630, 632 may have a diameter D2, where 0.5(D2)>=D3, and D2 may befrom about 0.2 mm to about 35 mm, or from about 14.3 mm to about 17.3mm, or from about 16.0 mm to about 16.2 mm. While the variation of thespring assembly described here may have two sensors, other variations ofspring assemblies may have three or more sensors as desired, e.g., 3, 4,5, 6, 8, 10 or more. Each of the sensors may drive individualnotification mechanisms, or may drive two or more notificationmechanisms. The sensors 626, 628 may also be used to detect when one orboth the springs 602, 606 break, which may result in the sudden increasein coil diameter.

Additionally or alternatively, the springs 602, 606 may have a pluralityof stripes oriented transversely to the length of the springs, where thespacing between the stripes may vary along the length of the springs(e.g., the spacing between stripes is directly related to the locationof the stripes on the length of the spring). One or more opticalsensors, e.g., a barcode scanner or laser backscatter sensor, may beprovided to detect the stripe spacing of the springs at a referencelocation, which may map to slidable seal location. Optical sensors maybe at a proximal location, e.g. longitudinally adjacent to the sensors626, 628, or may be located anywhere along the length of the springs.The rotary encoders described above may provide graded type outputs thatnot only indicate a charged or depleted configuration, but also provideoutputs that indicate intermediate configurations, e.g., suction deviceis about 100%, about 80%, about 50%, about 30%, about 10%, about 0%,charged or depleted. The notification mechanism may be adapted and/orconfigured to generate an alarm based on one or more intermediateconfigurations as desired.

Alarm systems with optical sensor mechanisms may also be used to detectthe position of the slidable seal. For example, an optical sensor may belocated at a proximal location (i.e., in proximity to the location ofthe slidable seal when the suction device exhausted or nearly exhausted,or at any location along the length of the suction device) that isconfigured to detect a certain optical cue on the slidable seal. Forexample, the slidable seal may have markings with a certain color,pattern (e.g., striped, dotted, zig-zag, etc.), reflectance orabsorbance property that may be detected by an optical sensor, which maydrive a notification mechanism to indicate that the slidable seal is atthe location of the optical sensor, i.e., the suction device isexhausted or depleted. Examples of optical sensors that may includeinfrared sensors, photodiodes, CCD devices, and the like.

Some optical sensors may be configured to detect an opticalinterference. For example, the housing of a suction device may besubstantially transparent or translucent, while the slidable seal may besubstantially opaque. An interference sensor located at a proximalportion of the clip, at the location where the slidable seal may be whenthe suction device is exhausted or depleted. The interference sensor maydetect an occlusion or blockage of light that may result from themovement of the opaque slidable seal when the device is exhausted, andtrigger the notification mechanism accordingly. An alarm systemcomprising an optical sensor may be detachably coupled to the suctiondevice, such that they may be removed from a depleted suction device andattached to a different (e.g., newly charged) suction device. In thisway, the alarm system may be reused for multiple sessions of reducedpressure therapy.

Certain variations of suction devices may comprise a pressure transducerthat may directly measure the pressure in the suction chamber, andsignal a notification mechanism according to the measured pressure. Thepressure transducer may be located at a distal portion of the suctionchamber. Optionally, there may be a display or monitor that indicatesthe exact pressure being applied to a tissue region. Notificationmechanisms may be configured to generate alerts according to certainpressure levels, as desired.

Certain variations of suction devices may also comprise liquid sensorsthat detect the presence of any fluids within the suction chamber. Analarm device may comprise a liquid sensor interface that receives thesignal from the suction device liquid sensor, and drives a notificationmechanism to notify the patient and/or practitioner when there is liquidin the suction chamber. Some types of liquid sensor mechanisms may alsoprovide data about the quantity of liquid in the suction chamber, whichmay trigger an alert for the patient and/or practitioner to empty orreplace the suction device. For example, some liquid sensor mechanismsmay sense the location of a float within the suction device chamber,where the float moves according to the quantity of air and/or fluids inthe chamber. In some variations, the float may comprise one or moremagnetic components that may be detected by any of the magnetic fieldsensitive mechanism described above. The detected location of the floatmay activate the notification mechanism to generate an alert.

Suction devices may be retained in an alarm device in a particularorientation. Various features on the housing of the suction device maycorrespond to and/or be aligned with features on the alarm device tohelp ensure a certain alignment and/or orientation when the suctiondevice is coupled to the alarm device. For example, one or more surfacestructures of the suction device housing and the alarm device may beconfigured to help ensure precise positioning of the suction device withrespect to the alarm device. The interface between the suction devicehousing and the alarm device may also comprise features that secure thesuction device in a desired alignment with the alarm device. In somevariations, the suction device and/or alarm device may be configuredsuch that the suction device may be retained in the alarm device in aplurality of orientations, as described further below. Examples ofsurface structures that may retain the alignment and position betweentwo surfaces may include interlocking flanges or hooks, interlockingslits or seals, hook and loop engagement, a protrusion and a recesscoupled by friction-fit, snap-fit structures, and the like. Examples ofsuction and/or alarm devices with features for alignment are describedbelow.

In some variations, the suction device housing may have one or moreprotrusions or grooves that are complementary to one or more grooves orprotrusions on the alarm device, e.g., form a mechanical interfit. Forexample, as depicted in FIG. 4D, the alarm device 404 may have one ormore protrusions 440 that fit into recesses 441 on the housing of thesuction device 400. In some variations, the suction device housing mayalso have curved grooves along its surface to accommodate the portionsof the alarm device that contact the suction device. Alternatively oradditionally, the suction and alarm devices may have snap latches andsnap grooves at corresponding locations.

Suction and alarm devices with different sensor mechanisms may havedifferent surface structures. This may help to ensure that only suctionand alarm devices with compatible sensor mechanisms may be coupledtogether. For example, attachment clips with magnetic sensors may havealignment features that form an interfit with the alignment features ofsuction devices with a magnetic component in the sliding seal, but donot interfit with the alignment features of suction devices without amagnetic sliding seal. For example, the alignment features of thesuction device 200 may not be compatible with the alignment features ofthe alarm device 310.

In other variations, suction and alarm devices may have electricalcomponents that correspond to each other to help ensure that deviceswith compatible sensor mechanisms are coupled together. For example, thesuction device may have a conductive element with a particular shapethat corresponds to the location of one or more electrical pins on thealarm device. When the conductive element of the suction device is inalignment with the one or more pins on the alarm device, an electricalsignal is provided to a microcontroller of the alarm system to indicatethat the suction and alarm devices are compatible and/or are properlyassembled together. In some variations, power is provided to themicrocontroller only when certain pins on the alarm device are shortedtogether by the conductive element of the suction device. In somevariations, the alarm device may comprise one or more electricalcontacts configured to align with corresponding conductive elements onthe suction device such that the alarm device is powered only when asuction device is placed within the alarm device such that theconductive elements are aligned with the one or more electricalcontacts. Additionally or alternatively, the alarm device may comprise apower switch that is configured to be depressed by a suction device thatis retained within the alarm device. Depressing the power switch maycomplete a circuit and connect a power source to an alarm systemmicrocontroller that may be included with the alarm device. When thesuction device is removed from the alarm device, the pressure on theswitch may be released, thereby disconnecting the power source to thealarm system microcontroller. The power switch may be a tactile switch,or any suitable mechanical or electrical switch mechanism. For example,an alarm device may comprise a tactile switch located on the inside ofthe device (e.g., a back panel of the alarm device that is to receive asuction device). Insertion of a suction device into the alarm device maypush on the tactile switch to power the alarm system on, and removal ofthe suction device from the alarm device may release the pressure on theswitch to power the alarm system off. Such power switch mechanisms maybe used to reduce power consumption of the reduced pressure therapysystem by helping to ensure that the alarm device does not draw anypower from the power source in the absence of a suction device.

FIGS. 14A-14C schematically depicts one example of an electricalmechanism that may be used to ensure that suction and alarm devices arecompatible. Such an electrical mechanism may also be used to indicatethe orientation of the suction device with respect to the alarm deviceso that a microcontroller on the alarm device may activate theappropriate sensors for depletion detection. In some variations, thismechanism may also be used to power the alarm system only when thesuction device is retained in the alarm device. A suction device 1400may comprise a conductive element 1402 that is accessible to an alarmdevice. The conductive element 1402 may have any geometry that issuitable for alignment purposes. For example, the conductive element1402 may have an elongate portion 1404 along a length of the suctiondevice 1400, and may also comprise an end portion 1406 thatsubstantially extends from the elongate portion 1404. The conductiveelement may be located along a central axis of the suction device, ormay be offset from the center. The overall geometry of the conductiveelement 1402 may be asymmetric or symmetric, depending on theconfiguration of electrical pins or pads on the alarm device. FIG. 14Bschematically illustrates the positioning of suction device 1400 withrespect to a plurality of pins on an alarm device. In some cases, thepins may be electrically isolated until coupled by a conductive elementon the suction device. The pins 1410, 1412 and 1414 are schematicallydepicted, but for the sake of simplicity, the alarm device is not shown.FIG. 14B depicts a first orientation 1420 of the suction device, wherethe conductive element 1402 on the suction device electrically couples afirst pin 1410, a second pin 1412, and a third pin 1414 together.Shorting these three pins together may send a first electrical signal toan alarm system microcontroller to indicate that the suction device isin the first orientation 1420. FIG. 14C depicts a second orientation1422 that is a 180 degree rotation from the first orientation 1420. Inthe second orientation 1422, the first pin 1410 and the second pin 1412are electrically coupled, however, the third pin 1414 is electricallyisolated from the first and second pins. Shorting the first and secondpins but not the third pin may send a second electrical signal to themicrocontroller to indicate that the suction device is in the secondorientation 1422. In some variations, power may be supplied to themicrocontroller only when the suction device 1400 is in the firstorientation 1420 or second orientation 1422, but not in the otherorientation. While the conductive element 1402 on the suction device andthe pins 1410, 1412, 1414 on the alarm device are configured to indicatetwo orientations, other suction devices may have one or more conductiveelements with different geometries that correspond to three or more pinson the alarm device to indicate any number or orientations.

FIGS. 14D and 14E depict one example of a suction device 1430 and analarm device 1440 that have an electrical mechanism that may be used fororientation identification, and/or to ensure that suction and alarmdevices are compatible. The electrical mechanism may also be used as apower switch such that alarm device 1440 is not powered on until thesuction device 1430 is retained therein. The suction device 1430 maycomprise a conductive element 1432, and the alarm device 1440 maycomprise a first pin connector 1442 and a second pin connector 1444located such that the conductive element 1432 and the pin connectorscontact each other when the suction device 1430 is placed within thealarm device 1440. As illustrated in FIG. 14D, the conductive element1432 is located along a side portion of the housing 1434 of the suctiondevice. The conductive element 1432 may have any suitable geometry, forexample, it may have an elongate portion 1436 that extends along alongitudinal axis of the suction device, and an end portion 1438 thatextends transversely to the elongate portion 1436. Portions of theconductive region 1432 may have any number of tapered, curved, rounded,etc. regions, as may be desirable. The location of the first connector1442 and the second connector 1444 of the alarm device 1440 maycorrespond to the location of the conductive element 1432 of the suctiondevice when retained in the alarm device. As illustrated in FIG. 14E,the first connector 1442 may comprise two pins 1443 a, 1443 b, and thesecond connector 1333 may comprise three pins 1445 a, 1445 b, 1445 c,however, it should be understood that an alarm device may have anynumber of connectors, and each connector may have any number of pins.The connectors on the alarm device may correspond to the pin pads of analarm system circuit, such as the alarm system circuit of FIG. 11, whichwill be described below. The number of pins on a connector may or maynot match with the number of pins on the pin pad corresponding to thatconnector. The number of pins on each connector or pin pad may varyaccording to the alarm system circuitry.

While alarm devices may have connectors configured to be shorted by aconductive element on a suction device have been described above,alternatively or additionally, suction devices may have an alarm systemwith connectors, and the alarm device may have a conductive elementconfigured to short the suction device connectors. For example, invariations where the suction device is electrically powered or has analarm system that is electrically powered, the suction device may haveelectrical connectors that interface with a conductive element on theattachment feature. These electrical connectors may act as a powerswitch for the suction device, and/or an orientation and/or acompatibility interface between the suction device and alarm device,such that the suction device is not electrically activated untilretained within the alarm device.

Various types of visual, audio, and tactile alerts generated by variousnotification mechanisms may be used with any of the sensor and/ordetection mechanisms described above. In some examples, the alert may bean audio signal (e.g. a buzzer or ringing sound), a visual signal (e.g.flashing colored light) or a tactile signal (e.g. vibration from anasymmetric weight attached to a rotary motor), or a combination thereof.Other signals may include data signals that may be connected wirelesslyor by wired connection to one or more displays and/or electronichealthcare/nursing record databases. These displays and/or electronicdatabases may be local (e.g. in the clip or a pocket-sized mobiledevice) to the user, or remote (e.g. the nursing station of thetreatment facility, online electronic healthcare record database or theuser's personal computer), and utilize any of a variety datatransmission modalities (e.g. cellular networks and/or internet).

One example of a notification circuit 408 is depicted in FIG. 5. Thenotification circuit 408 may comprise an open circuit 432 with alarmcontacts 406 and 407 as terminal nodes, and a tone generator 434configured to drive speakers 430. All the components may be powered by abattery 436, which may provide a DC voltage that is appropriate forselected tone generator 434, e.g., from about 1.5 V to about 4.5 V. Thetone generator 432 may be activated depending on the connectivity of theopen circuit 432. Additional features may be included with thenotification mechanism 408 to adjust the sound produced by the tonegenerator 434, the volume of the sound, and the duration that the soundis produced, etc. Variations of notification mechanisms may be used toactivate different notification circuits to generate an alarm (e.g.,visual or tactile alarms, as well as wireless signal generators), andmay be included as separate modes that may be activated by thepractitioner and/or patient. Notification circuits may also comprisememory components that may be configured to retain information aboutpast alarm events, pre-programmed instructions, snooze functions, andthe like. Notification circuit 408 may be located on the alarm device oron the suction device, as desired.

Additionally or alternatively to visual and/or audio alerts,notification mechanisms may issue electronic messages, such as textmessages, e-mails, pages, etc., to indicate the state of the suctiondevice, and whether or not the device needs to be replaced or emptied.The alerts may be provided to local monitors, such as the patient and/orattending medical practitioner, and/or may be provided to remotemonitors, such as a medial practitioner who may be at a removedlocation. In some variations, the remote monitor may send a command tothe suction device alarm system to issue an alert to prompt the patientto check on the suction device.

FIG. 9 depicts a block diagram representation of one variation of analarm system 900. The alarm system 900 may comprise a microcontrollermodule 908 that has a microcontroller chip that may be programmed toaccept sensor and/or user inputs and drive indicator outputs. Forexample, the microcontroller module 908 may receive input signals from asuction device orientation module 902, a sensor module 904, and a userinput module 906. The orientation module 902 may provide information tothe microcontroller module 908 regarding the position and/or orientationof the suction device with respect to the alarm device. The sensormodule 904 may have one or more sensor mechanisms as described above,and may have, for example, one or more reed switches. The user inputmodule 906 may comprise switches (e.g., power switch, toggle switches,etc.), buttons, dials, keyboards, and the like which may providepatient-specific information to the microcontroller 908, as well as toregulate the state of the alarm system 900. In addition to these inputs,the microcontroller module 908 may drive any number of output modules.For example, the microcontroller module 908 may drive a light-emittingdiode (LED) module 910 that may be used as optical notifications to thepatient, and/or may be used to backlight a display, such as a monitor.Outputs from the microcontroller may also be used to drive an indicatormodule 912 comprising notification circuits such as the ones previouslydescribed. In some variations, the indicator module 912 may compriseamplifiers that may augment the notification signal, whether audio,optical, tactile, electronic or otherwise, to help ensure that thepatient and/or practitioner is made aware of the status of the alarmsystem. For example, the microcontroller may provide a signal to anaudio amplifier that may in turn drive a speaker to generate an audiblealert.

The various modules depicted in FIG. 9 may be located on either or boththe suction device and alarm device. For example, the microcontrollermodule 908, optical notification module 910, user input module 906, andindicator module 912, may be located on the alarm device, while thesensor module 904 and the orientation module 902 may be located on thesuction device. Alternatively, the components of both sensor module 904and the orientation module 902 may be located on both the suction andalarm devices. The optical notification module 910 and the user inputmodule 906 may also be on the suction device, as may be desirable. Inother variations, all the modules depicted in FIG. 9 may be located onlyon the alarm device or only on the suction device. In still othervariations, the modules depicted in FIG. 9 may be detachably coupled tothe suction and alarm devices.

One variation of a system that comprises two reed sensors and generatesan alarm based on signals from the reed sensors is depicted in FIG. 10A.The alarm system 1000 may comprise a first reed switch module 1004 and asecond reed switch module 1006 that detect the position of the slidingseal within a suction device, and provide electrical signals, e.g.,voltage or current signals, that correlate with the position of thesliding seal to a microcontroller module 1012. The microcontrollermodule 1012 may comprise a voltage sensor 1010. In some cases, themicrocontroller module may comprise a programmable microcontroller ormicroprocessor with an embedded voltage sensor, for example, asystem-on-a-chip microcontroller unit (MCU), such as any MCU in theC8051F93x-C8051F92x MCU family (Silicon Labs Inc of Austin, Tex.), forexample. Any microcontroller with the appropriate power consumption(i.e., low power consumption), size (i.e., small size), andprogrammability (i.e., flexible software programming interface,compatibility with a variety of electronic components) may be used. Themicrocontroller module 1012 may receive inputs from a suction deviceorientation module 1002 which may be used to interpret the inputs fromother modules in the alarm system 1000. The alarm system 1000 may alsocomprise a user switch module 1008 which may allow the patient toactivate or deactivate the system, as well as to providepatient-specific data to the alarm system. The microcontroller module1012 may drive a number of output modules, such as a LCD sense indicatormodule 1014, a LCD battery indicator module 1016, a LCD alarm indicatormodule 1018, a LED backlight module 1020, and an amplifier module 1022.In some variations, the microcontroller module may drive the LCD senseindicator module 1014 or a LCD segment to indicate that a suctiondevice/cartridge is properly installed in the alarm device and/or thatthe alarm system is powered. For example, the LCD sense indicator module1014 may be turned on or activated to indicate that there is a validand/or compatible suction device coupled to the alarm device, and may beturned off or deactivated to indicate that there is no valid and/orcompatible suction device coupled to the alarm device. Additionally oralternatively, the microcontroller module 1012 may drive radiofrequencytransmitters or other electronic messaging devices to provide an e-mailor a text to a patient and/or practitioner to alert them of the state ofthe suction device.

One example of an orientation circuit that may be used with an alarmdevice orientation module is depicted in FIG. 10B. Orientation circuit1031 may comprise a first pin pad 1033 and a second pin pad 1038, whereeach pin pad may comprise one or more pins in any arrangement thatcorresponds to a conductive element in a suction device, as previouslydescribed. The first pin pad 1033 has a first pin 1034 and a second pin1036, where electrically shorting them together may indicate a firstsuction device orientation. The first pin pad 1033 may be connected as aswitch to a battery 1030 that may be configured to supply power to thealarm system, e.g., via a connection to the microcontroller module atthe first terminal 1040. When the first pin 1034 and the second pin 1036are electrically isolated, the first pin pad 1033 may be as an opencircuit, and the battery 1030 may be disconnected from the electricalcomponents of the alarm system. Shorting the first pin 1034 and secondpin 1036 together may act to close the circuit such that the battery1030 may provide power to the alarm system, e.g., by turning on themicrocontroller module, etc. An optional LED diode 1046 connected to thefirst terminal 1040 may be activated when the first and second pins areshorted, which may provide a visual indication to the user that power isprovided to the alarm system. The second pin pad 1038 may have a thirdpin 1039, where electrically shorting all three pins 1034, 1036, and1039 may indicate a second suction device orientation. The connectivityof the second pin pad 1038 may be indicated to the microcontrollermodule via a second terminal 1042. Other variations of orientationcircuits may have different a different number of pin pads and pins in avariety of arrangements. The battery 1030 may store sufficient energy topower the one or more electronic components of the alarm system, and maybe selected according to the desired shelf life, service life, size,voltage, compatibility with other alarm system components, and/ordischarge capacity. Any suitable batteries may be used with theorientation circuit 1031, for example, a battery with a shelf life of 10years, service life of at least 8 weeks, such as the 3V CR2032 battery.Optionally, the orientation circuit 1031 may have a battery sensor 1032that may provide an indication of how much energy is stored in thebattery 1030, and activate a LED that may prompt the patient and/orpractitioner to replace the battery or the alarm system. In certainvariations, the alarm system may be powered by plugging into a wallsocket instead of, or in addition to, using a battery.

One example of a sensor circuit that may be used with an alarm devicesensor module is depicted in FIG. 10C. The sensor circuit 1050 maycomprise any number and types of sensors and/or switches, as previouslydescribed, for example, a first reed switch 1052 and a second reedswitch 1054. When the slidable seal of a suction device is in proximityto the first reed switch 1052, it will close the switch and communicatethe proximity of the slidable seal to the microcontroller module via aconnection through a first terminal 1053. When the slidable seal of thesuction device is in proximity to the second reed switch 1054, it willclose the switch and communicate the proximity of the slidable seal tothe microcontroller module via a connection through a second terminal1055. Based on the data from the orientation module, the microcontrollermodule will make a determination as to the depletion state of thesuction device. The sensor circuit 1050 may also comprise auser-activated switch 1056 that when closed, will activate the first andsecond reed switches. For example, the third terminal 1057 that isconnected to a node of the user-activated switch 1056 may be connectedto the microcontroller module, which may provide a certain voltage orcurrent level that may only be conveyed to the first terminal 1053and/or second terminal 1055 if the user-activated switch 1056 is closedand either or both the reed switches 1052, 1054 are closed. Othermechanisms for activating and/or deactivating the sensor circuit 1050,e.g., ON-OFF switches, may be used as appropriate.

One example of an amplifier circuit that may be used with an alarmdevice orientation module is depicted in FIG. 10D. The amplifier circuit1060 may comprise an amplifier chip 1062, which may receive signals fromthe microcontroller module via a first terminal 1066 and/or a secondterminal 1068, and drive a speaker 1064 according to the microcontrollersignals. Any suitable amplifier chip may be used in the amplifiercircuit 1060, for example, the LM4675 amplifier. Amplifiers may be usedwith any desirable type(s) of indicators, including auditory, vibratory,visual, electronic, etc. to augment the activity of the indicators.

LED circuits that may be used with an alarm device alarm system maycomprise a LED array with one or more LEDs driven by an input bus fromthe microcontroller module. Each LED in the LED array may represent thestatus of a component in the alarm system and/or the state of themicrocontroller. For example, individual LEDs in the LED array mayrepresent the status of the battery, activation of the microcontroller,orientation of the suction device with respect to the alarm device, thedepletion or charging of the suction device, alarm mode, sleep or activemode, power mode, etc. The LED array may also be used as a LCDbacklight, as appropriate. Optionally, the LED circuit may also comprisea zener diode array that may be used as a shunt voltage regulator toprevent sudden voltage surges. Alternatively, certain alarm systems maycomprise an array of LCD segments or other electronic devices that maybe used to represent the status of one or more components in the alarmsystem.

The components of any of the alarm systems described above may bemounted on a printed circuit board in accordance with their desiredposition on the alarm device. For example, the sensor mechanisms thatare triggered to the location of the slidable seal of a suction devicecoupled to the alarm device may be positioned to correspond to thelocation of the seal in the charged and/or depleted configuration. FIG.11 depicts one example of an alarm system 1100 with its componentsmounted on a printed circuit board 1101. The alarm system 1100 maycomprise a microcontroller 1102 that receives signals from a firstsensor mechanism 1104 located on a first side of the printed circuitboard 1101 and a second sensor 1106 located on a second side of theboard, where the second side is opposite the first side. The alarmsystem 1100 may also comprise a first pin pad 1108 and a second pin pad1110 that may be used to determine the orientation of the suction devicewith respect to the alarm device. For example, the first connector 1442depicted in FIG. 14E may correspond to the first pin pad 1108, and thesecond connector 1444 of FIG. 14E may correspond to the second pin pad1110. The microcontroller 1102 may use the inputs from the first sensormechanism 1104, second sensor mechanism 1106, first pin pad 1108, andsecond pin pad 1110 to determine the depletion or charge state of thesuction device. The state of the suction device as determined by themicrocontroller 1102 may be used to drive an amplifier module 1112 togenerate any of the indicators descried above. The microcontroller 1102may also be used to drive a LCD-LED array 1114 that may provideinformation to a patient and/or practitioner, e.g., by providingbacklighting to a monitor, binary encoding of the suction device state,etc. While the printed circuit board 1101 is an oblong elliptical shape,it should be understood that it may have any geometry as suitable forthe alarm device or clip.

One example of an alarm device 1200 that may use the alarm systemsdescribed above is depicted in FIG. 12A. The alarm device 1200 may havean alarm system 1202 embedded along a portion of the alarm device todetect the position of the slidable seal within a suction device. Forexample, the alarm system 1100 may be embedded along the longestdimension, e.g. its length, of the alarm device 1200. The alarm system1202 embedded within the alarm device 1200 may comprise an audio speaker1204, indicators 1206, and a user-activated switch 1208. The indicators1206 may be configured to signal the state of the alarm system (e.g.,active or inactive), the state of the suction device (e.g., depleted orcharged, etc.), the state of the battery (e.g., charged or drained,etc.), and the state of any of the components in the alarm system. Theuser-activated switch 1208 may be a press-button or slide-button thatmay be used to activate backlight illumination for the indicators 1206or to snooze an activated indicator or alert. FIG. 12B depicts anexample of a suction device 1220 that may be retained within the alarmdevice 1200. In this example, a first sensing mechanism of the alarmsystem (e.g., a first reed switch) may be located at a proximal portion1222 of the alarm device 1200 while a second sensing mechanism (e.g., asecond reed switch) may be located at a distal portion 1224. The suctiondevice 1220 may comprise a conductive element as previously described sothat the alarm system microcontroller may determine the orientation ofthe suction device 1220 with respect to the alarm device 1200.

Another example of an alarm device 1500 that may use the alarm systemsdescribed above is depicted in FIG. 15A. The alarm device 1500 may havean alarm system 1502 embedded along a portion of the alarm device todetect the position of the slidable seal within a suction device. Thealarm system 1502 embedded within the alarm device 1500 may comprise anaudio speaker 1504, a display 1506, and a user-activated switch 1508.The display 1506 may comprise, for example, light bulbs, or an LED, LCD,OLED or other type of optical display. The display 1506 may beconfigured to signal the state of the alarm system (e.g., active orinactive), the state of the suction device (e.g., depleted or charged,etc.), the state of the battery (e.g., charged or drained, etc.), andthe state of any of the components in the alarm system. For example,display 1506 may present an indicator 1506 a may be in the shape of acircle and used to indicate that the system is powered on and active,i.e. that the suction device has been properly inserted and seated, andthat there is adequate battery power to perform its detection and alarmfunctions. In other examples, the indicator 1506 a may be configured toidentify the current suction capacity of a suction device retainedwithin the alarm device. The indicator 1506 b may be used to indicatethe status of the battery. The battery status may indicate a binarystate (powered/unpowered), or may be configured to indicate multiplebattery states, with three or more levels of battery power. Theindicator 1506 c may be used to indicate the alarm mode (e.g., alarmfrequency, pre-programmed modes, snooze mode, etc.). The user-activatedswitch 1508 may be a press-button or slide-button that may be used toactivate backlight illumination for the indicators 1506 or to snooze anactivated indicator or alert (e.g., by silencing an audible alarm for apre-selected period of time). An alarm device may also comprise one ormore side connectors and/or one or more panel connectors. As depicted inFIG. 15B, the alarm device 1500 comprises a clip comprising one or moreside connectors 1516 and a power supply button 1517. These connectorsmay be used as described above, for example, as a power switch, and/ororientation and/or compatibility verification mechanism. The powersupply button 1517 c may be depressed when a suction device is retainedin the alarm device, thereby closing an open circuit and supplying powerto the alarm system.

FIG. 15C depicts an example of a suction device 1520 that may beretained within the alarm device 1500. The suction device 1520 maycomprise measurement markings 1521 on a transparent portion of thesuction chamber 1523 that may be used to quantify the position of apiston, and/or the quantity of a fluid, or volume of a solid or gelcontained in the chamber. The suction device 1520 may also comprise oneor more protrusions configured to engage with the alarm device, i.e., bysnap-locking, such that an electrical connection may be made between aconductive element on the suction device and connectors on the alarmdevice. The protrusions may also help the alarm device retain thesuction device with a certain alignment. For example, first and secondprotrusions 1526, 1528 may be located at a proximal portion 1522, whilethird and fourth protrusions 1530, 1532 may be located at a distalportion 1524 to retain the position of the suction device 1520 withinthe alarm device. In other variations, a suction device may comprise oneor more recesses that correspond to one or more protrusions on the alarmdevice. The protrusions may be symmetrically arranged on the suctiondevice (e.g., along a longitudinal and/or transverse axis) orasymmetrically arranged, as may be suitable. The protrusions may helpensure that a suction device retained in the alarm device does not moveor change configuration during reduced pressure therapy. The locationand geometry of the protrusions of the suction device may be configuredsuch that the suction device may be retained in the alarm device in avariety of orientations, as described further below. Additionally oralternatively, engagement mechanisms such as magnetic, adhesive,hook-and-loop, etc. may be used to couple the suction and alarm devices,as described previously. A back panel of the alarm device 1500 retainingthe suction device 1520 is depicted in FIG. 15D. The alarm device 1500may optionally comprise a first loop portion 1510 and a second loopportion 1512, which may be used for coupling the alarm device to a beltor strap. In some variations, the alarm device 1500 may be coupled to abelt or strap by hook-and-loop engagement, snap-lock, buttons, clasps,adhesives, and the like. The suction device 1520 may comprise aconductive element as previously described so that the alarm systemmicrocontroller may determine the orientation of the suction device 1520with respect to the alarm device 1500.

In some variations, the suction device may be configured to be retainedby the alarm device in a plurality of orientations, and the alarm devicemay be configured to detect the depletion state of the suction device(e.g., fully charged, partially charged/depleted, or fully depleted)regardless of the orientation in which the alarm device retains thesuction device. For example, the suction device may be retained in thealarm device as shown in FIG. 15C, where the superior portion 1542 isfacing up and the left side 1545 is closest to the alarm system 1502.The suction device 1520 may also be retained in an orientation where theinferior portion 1543 is facing up and the right side 1544 is closest tothe alarm system 1502. Optionally, the suction device 1520 may also beretained in an orientation where the relative position of the distal end1546 and the proximal end 1547 are switched. FIG. 19 schematicallyillustrates the various orientations that a suction device 1900 may beretained in an alarm device. For example, the suction device 1900comprising a suction chamber 1902 and a sliding seal assembly 1904 maybe configured to be retained such that the superior portion 1920 isfacing up. The alarm device may also be configured to retain the suctiondevice 1900 in an orientation that is rotated around longitudinal axisA1 (e.g., 180°, such that the relative positions of the superior 1920and inferior 1921 portions are switched, and the relative positions ofthe left 1922 and right 1923 sides are switched). The alarm device mayalso be configured to retain the suction device 1900 in an orientationthat is rotated around transverse axis A2 (e.g., 180°, such that therelative positions of the distal 1925 and proximal 1926 portions areswitched, and the relative positions of the superior 1920 and inferior1921 portions are switched). The alarm device may be configured toretain the suction device 1900 in an orientation that is rotated aroundboth axes A1 and A2 (e.g., rotated 180° around axis A1 and rotated 180°around axis A2 such that the relative positions of the superior 1920 andinferior 1921 portions, distal 1925 and proximal 1926 portions, and left1922 and right sides 1924 are interchanged with each other, etc.).Accordingly, the alarm device may be configured to detect when thesuction device 1900 is in a fully depleted state (e.g., sliding sealassembly 1904 has moved to a proximal portion of the suction chamber) insome or all of these retention orientations. For example, some alarmdevices may be configured to detect the depletion state of a suctiondevice in two retention orientations (e.g., in a first orientation andin a second orientation, where the second orientation is a front-to-backrotation of the first orientation). Some alarm devices may be configuredto operate with a device that may be retained in three or moreorientations (e.g., in a first, a second, a third, and a fourthorientation, where the second orientation is the first orientationrotated 180° around axis A1, the third orientation is the firstorientation rotated 180° around axis A2, and the fourth orientation isthe first orientation rotated 180° around axis A1 and rotated 180°around axis A2).

Suction devices may also be configured to be retained in the alarmdevice in a plurality of orientations. For example, suction devices maycomprise protrusions similar to those described and depicted in FIGS.15C-15D that can accommodate a plurality of retention orientations.Suction device may also comprise a sliding seal assembly with two ormore magnetic elements, so that the location of the sliding sealassembly may be detected by the alarm device regardless of the retentionorientation. Alternatively, alignment protrusions on a suction devicemay constrain the retention orientation of the suction device, such thatthe suction device may be retained in the alarm device in one or twoorientations. In some variations, the alarm device is configured to onlydetect the depleted state of the suction device. For example, a suctiondevice 1900 may have a first magnetic element 1914 on the left side 1922of the sliding seal assembly and a second magnetic element 1915 on theright side 1924 of the sliding seal assembly, as schematically depictedin FIGS. 19B-19D. The alarm device may comprise a first reed switch 1906at a first location and a second reed switch 1908 at a second locationseparate from the first location (e.g., the second reed switch 1908 maybe proximal to the first reed switch). The suction device may beretained by the alarm device such that the location of the sliding sealassembly 1904 in the fully charged state is proximal to the location ofthe first reed switch 1906 of the alarm device, as depicted in FIG. 19B.The suction device 1900 may comprise a tab, shoulder, or any suitablestop structure (e.g., a wall of a distal cap) that may prevent thesliding seal assembly 1904 from moving to the distal-most portion of thesuction chamber. When the suction device is this fully charged state,the location of the magnetic elements 1914, 1915 is such that they areundetected by the first reed switch 1906. When the suction device isfully depleted, the sliding seal assembly may be at the location 1905depicted in FIG. 19C, and at least one of the magnets 1914, 1915 may beclose enough to be detected by the second reed sensor 1908, therebytriggering an alert. The suction device 1900 may comprise a proximaltab, shoulder, or any suitable stop structure (e.g., a wall of aproximal cap) that may prevent the sliding seal assembly 1904 frommoving further in the proximal direction. This particular arrangement ofthe alarm device with the suction device allows for the detection of thedepleted state regardless of the orientation with which it is retainedin the alarm device. For example, when the retention orientation of thesuction device 1900 depicted in FIG. 19B is rotated 180° around axis A2,the device may be oriented as depicted in FIG. 19D. In this retentionorientation, the magnetic elements 1914, 1915 of the sliding sealassembly in the fully charged configuration may be undetectable by thesecond reed switch 1908, but when the suction device is in the fullydepleted configuration where the sliding seal assembly is at location1905, the magnets 1914, 1915 may be detected by the first reed switch1906. Such an arrangement of reed switches in the alarm device andmagnets in the suction device may help to reduce patient confusion wheninstalling the suction device in the alarm device, and may help toensure that the alarm system is able to alert a patient when the suctiondevice is depleted, regardless of the suction device orientation in thealarm device.

As described previously, the attachment protrusions of a suction devicemay help to ensure that the reed switches and magnetic elements aresituated in a specific configuration with respect to each other (e.g.,such that the alarm system may detect the depleted state of the suctiondevice regardless of the retention orientation). For example, thelocation of the first and second reed switches 1906, 1908 may define aline segment L1 with a midpoint 1912. The position of the sliding sealassembly 1904 in the fully charged state and the position of the slidingseal assembly in the depleted state may define a travel path along aline segment L2 with a midpoint 1910, as depicted in FIG. 19C. Thetravel path may extend along the entire length of the suction chamber,or may extend along a portion thereof (e.g., ½, ⅔, ¾, of the length ofthe suction chamber, centered or offset from the center of the suctionchamber). The attachment protrusions may be positioned such that themidpoint 1910 of the sliding seal assembly travel path is offsetproximally from the midpoint 1912, for example, by an offset amount L3.Shifting the midpoint 1910 by offset L3 from the midpoint 1912 may helpto ensure that when the suction device 1900 is in the fully chargedstate, the magnetic elements 1914, 1915 are not detectable by eitherreed switch, and when the suction device 1900 is in the fully depletedstate, the magnet elements 1914, 1915 are detectable by at least onereed switch, regardless of the retention orientation of the suctiondevice. For example, FIG. 19B depicts the location of the sliding sealassembly 1904 when the suction device 1900 is in the fully chargedstate. In such a location, the sliding seal assembly 1904 is notdetectable by reed switch 1906. When the suction device 1900 transitionsto the depleted configuration, the sliding seal assembly may be atlocation 1905, as depicted in FIG. 19C, and may be detectable by reedswitch 1908. FIG. 19D depicts the suction device 1900, but retained inthe alarm device after it has been rotated 180° around the axis A2 fromthe configuration shown in FIG. 19B. In the fully charged state and/orpartially depleted intermediate states, the magnetic elements 1914, 1915are not detectable by either reed switch 1908 or reed switch 1906.However, in the depleted configuration, the sliding seal assembly may beat location 1905, where it may be detectable by reed switch 1906.

The suction device may be configured to be retained in the alarm devicesuch that the distance of magnetic elements of the sliding seal assemblyto the nearest reed switch is less in the fully depleted state than inthe fully charged state. As such, the alarm device may detect when thesuction device is in the fully depleted state and generate an alert, butmay not detect when the suction device is in the fully charged state. Insome embodiments, the travel of the sliding seal assembly within thesuction device may be such that the distance of the magnetic elements tothe distal protrusions (e.g., protrusions 1530, 1532 of FIG. 15C) in thefully charged state may be greater than the distance of the magneticelements to the proximal protrusions (e.g., protrusions 1526, 1528).Variations of these arrangements may be contemplated to ensure thatregardless of the orientation of the suction device in the alarm device,the alarm system is able to detect when the suction device is depletedand to generate a signal to the patient.

In other variations, the suction device may be configured to be retainedin the alarm device such that the distance of magnetic elements of thesliding seal assembly to the nearest reed switch is greater in the fullydepleted state than in the fully charged state. In this variation, thealarm device may detect when the suction device is in the fully chargedstate, but not when it is in the fully depleted state, which may helpsignal that the suction device is properly installed.

While alarm devices comprising two reed switches have been described anddepicted herein, it should be understood that some variations may haveonly one reed switch. For example, one variation of a reduced pressuretherapy system may comprise a suction device comprising a sliding sealassembly with two magnetic elements and an alarm device comprising onlyone reed switch, as depicted schematically in FIG. 20. The alarm device2000 may be configured to detect the depleted state (and not the chargedstate) of the suction device 2010. The alarm device 2000 may comprise areed switch 2002 located at a proximal portion 2001, and one or morealignment tabs 2004 (e.g., one located on the left 2003 and right 2005side of the alarm device). The suction device 2010 may comprise asuction chamber 2011 with a sliding seal assembly 2014 in the suctionchamber, and one or more alignment protrusions 2016 along the left 2013and right 2015 sides. The alignment tabs 2004 may be located towards theproximal portion 2001. The alignment protrusions 2016 may be located inpositions that correspond to the location of the alignment tabs 2004,and may interlock with each other (e.g., by snap lock, etc.). Placementof the alignment features in an offset position (e.g., towards theproximal or distal end of the devices) may help a patient and/orpractitioner to install the suction device in a desired orientation withrespect to the alarm device. The suction device 2010 may be retained inthe alarm device 2000 such that the left 2013 and right 2015 sides ofthe suction device are aligned with the left 2003 and right 2005 sidesof the alarm device. The suction device 2010 may also be retained in thealarm device 2000 such that the right 2015 and left 2013 sides of thesuction device are aligned with the left 2003 and right 2005 sides ofthe alarm device (e.g., rotated 180° around the longitudinal axis).Optionally, the suction device 2010 may be retained by the alarm device2000 in an orientation where the relative position of the distal portion2018 and the proximal portion 2019 is interchanged (e.g., rotated 180°around a transverse axis from the orientation depicted in FIG. 20). Thealignment tabs 2004 may be configured to interlock with the alignmentprotrusions 2016 in this transversly-rotated orientation. In such anorientation, the alarm device 2000 may be able to detect the depletedstate of the suction device 2010. In some variations, suction devicesmay comprise a sliding seal assembly having only have one magneticelement, and may be retained in an alarm device in two or fewerorientations.

In alternative variations, the alarm device may comprise three or morereed switches, which may allow for the detection of additional suctiondevice configurations and orientations. Optionally, suction devices maycomprise sliding seal assemblies that have two or more magnetic elementsin various locations. The number and locations of reed switches andmagnetic elements on the suction device and alarm device may be variedin accordance with the desired retention orientation of the suctiondevice, as well as the number of suction device configurations that areto be detected.

Once the suction device has been detected to be in the fully depletedstate, the microcontroller of an alarm system may response according topre-programmed algorithms. For example, certain microcontroller modulesmay additionally comprise a programming interface that may allow scriptsand instruction sets to be downloaded into the microcontroller. In somevariations, the microcontroller may be programmed to implement a statemachine 1300, as represented by the state machine diagram depicted inFIG. 13. The microcontroller may activate certain alarm systemcomponents (e.g., LEDs, LCD screen, amplifiers, speakers, etc.) inaccordance to its current state as determined by sensor and/or userinputs. FIG. 13 merely depicts an example of a state machine that may beprogrammed into a microcontroller for used with an alarm system for asuction device, and it should be understood that a variety of statemachines (e.g., with more or less states) may be implemented as may besuitable. In some variations, the microcontroller may be programmed tobe in a “sleep” or low-power mode for the majority of its operation, and“wake” or activate every second or minute to check signals from thealarm system sensors and/or switches. In some variations, signal filtersmay be programmed into the microcontroller to help reduce false positivesignals. If an alarm condition is detected (e.g., low battery, suctiondevice nearing or at depletion, etc.), the microcontroller may remain inthe activated state to generate the necessary alerts and indicators totrigger an action on the part of the patient and/or practitioner. Themicrocontroller may be programmed to drive the alert or indicator modulefor a certain amount of time, e.g., 1 minute, 2 minutes, 5 minutes,etc., and may be dormant or snoozed for a certain amount of time, e.g.,1 minute, 10 minutes, 30 minutes, etc., before driving the alert orindicator module again. For example, the alert module may issue a soundfor 5 minutes (either continuously or in bursts), remain silent for 30minutes, and then sound for 5 minutes if the suction device is notreplaced. Optionally, a visual alert may accompany the audio alert. Asnooze function may be provided where the audio alert may be silencedfor a period of time (e.g., 5 minutes, 15 minutes, 25 minutes, etc.). Ifafter the period time has elapsed and the suction device has not beenreplaced, the audio alert may continue to sound. Other such functionsand modes may be programmed into the microcontroller as desired.

Although the embodiments herein have been described in relation tocertain examples, various additional embodiments and alterations to thedescribed examples are contemplated within the scope of the invention.Thus, no part of the foregoing description should be interpreted tolimit the scope of the invention as set forth in the following claims.For all of the embodiments described above, the steps of the methodsneed not be performed sequentially. Accordingly, it is not intended thatthe invention be limited, except as by the appended claims.

1. (canceled)
 2. A reduced pressure therapy system comprising: a suctiondevice comprising a suction chamber; and a fluid retention system havinga first state and a second state, comprising a carrier structure and anabsorbent material, wherein the absorbent material is retained by thecarrier structure in the first state. wherein the absorbent material isnon-hydrated and attached to the carrier structure in the first stateand hydrated and separated from the carrier structure in the secondstate.
 3. The system of claim 2, wherein the carrier structure isattached to the interior of the suction device in the first state. 4.The system of claim 2, wherein carrier structure attached to a distalportion of the suction chamber in the first state.
 5. The system ofclaim 4, wherein the carrier structure is attached by adhesives.
 6. Thesystem of claim 2, wherein the carrier structure has a shape thatcorresponds to a cross-sectional shape of the suction device.
 7. Thesystem of claim 2, wherein the suction chamber comprises an inletopening, and wherein the carrier structure comprises an aperture alignedwith the inlet opening in the first state.
 8. The system of claim 1,wherein the absorbent material comprises a superabsorbent material. 9.The system of claim 1, wherein the absorbent material is powder-like inthe first state, and gel-like in the second state.